Low-Carb Portobello Bun Chicken Burgers

Name: Low-Carb Portobello Bun Chicken Burgers
Prep time: 36 min
Cook time: 23 min
Total time: 59 min
Yield: 4 servings
Cuisine: American
Ingredients: 8 medium caps (about 4 inches wide) (640 g) portobello mushroom caps, stems removed, gills gently scraped out with a spoon, wiped clean; 2 tbsp (30 ml) extra-virgin olive oil; 1 tbsp (15 ml) balsamic vinegar; 2 cloves (6 g) garlic cloves, finely grated or minced; ¼ tsp (1½ g) kosher salt; ¼ tsp (½ g) black pepper, freshly ground; 1½ lb (680 g) ground chicken (thigh or 93% lean), cold, straight from the fridge; ¼ cup (28 g) fine almond flour; 1 large (50 g) large egg, lightly beaten; 3 cloves (9 g) garlic cloves, finely minced; 3 scallions (45 g) scallions, white and green parts thinly sliced; 1 tsp (2½ g) smoked paprika; 1 tsp (1 g) dried oregano; 1¼ tsp (6 g) kosher salt; ½ tsp (1 g) black pepper, freshly ground; 1 tbsp (15 ml) olive oil, for the grill grates; 4 slices (about 4 oz total) (112 g) sliced provolone cheese, at room temperature; ¼ cup (60 g) mayonnaise; 1 small clove (3 g) small garlic clove, grated to a paste; 2 tsp (10 ml) lemon juice, freshly squeezed; 1 tsp (5 g) Dijon mustard; 1 large (180 g) large ripe tomato, cut into 4 slices about ¼ inch (6 mm) thick; ½ small (40 g) red onion, sliced into thin rings; 1 cup, loosely packed (20 g) baby arugula

From the MyKitchenBank Kitchen

Juicy garlic-and-scallion chicken patties topped with melted provolone and sandwiched between two grilled, balsamic-garlic portobello caps instead of bread. Fresh, filling, and about 6 g net carbs per burger.

Prep: 36 min
Cook: 23 min
Wait: 28 min
Total: 1 hr 27 min
Makes: 4 burgers

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Ingredients

4 servings

For the mushroom buns
8 medium caps (about 4 inches wide) (640 g) portobello mushroom caps, stems removed, gills gently scraped out with a spoon, wiped clean
2 tbsp (30 ml) extra-virgin olive oil
1 tbsp (15 ml) balsamic vinegar
2 cloves (6 g) garlic cloves, finely grated or minced
¼ tsp (1.5 g) kosher salt
¼ tsp (0.5 g) black pepper, freshly ground
For the chicken patties
1½ lb (680 g) ground chicken (thigh or 93% lean), cold, straight from the fridge
¼ cup (28 g) fine almond flour
1 large (50 g) large egg, lightly beaten
3 cloves (9 g) garlic cloves, finely minced
3 scallions (45 g) scallions, white and green parts thinly sliced
1 tsp (2.5 g) smoked paprika
1 tsp (1 g) dried oregano
1¼ tsp (6 g) kosher salt
½ tsp (1 g) black pepper, freshly ground
1 tbsp (15 ml) olive oil, for the grill grates
4 slices (about 4 oz total) (112 g) sliced provolone cheese, at room temperature
For the garlic mayo and toppings
¼ cup (60 g) mayonnaise
1 small clove (3 g) small garlic clove, grated to a paste
2 tsp (10 ml) lemon juice, freshly squeezed
1 tsp (5 g) Dijon mustard
1 large (180 g) large ripe tomato, cut into 4 slices about ¼ inch (6 mm) thick
½ small (40 g) red onion, sliced into thin rings
1 cup, loosely packed (20 g) baby arugula

Equipment (9)

Gas or charcoal grill (or a large cast-iron grill pan)
Large mixing bowl
Shallow dish or rimmed plate for marinating the mushrooms
Rimmed baking sheet or plate lined with parchment for the patties
Spoon for scraping gills
Wide spatula and tongs
Instant-read thermometer
Small bowl for the garlic mayo
Grill brush and folded paper towel for oiling the grates

Steps

Before you start

Choose 8 portobello caps that are about 4 inches (10 cm) wide and fairly flat, so they stack neatly like buns and sit steadily on the grill.
Use ground chicken made from thigh meat, or at least 93% lean. Very lean breast-only mince makes dry patties.
Keep the chicken refrigerated until you are ready to mix. It is sticky, and cold meat is much easier to shape.
Wipe the mushrooms with a damp paper towel. Do not soak them, or they will turn soggy on the grill.
Read through the timing: the patties chill for 15 minutes while the grill preheats, and the mushrooms marinate during that time.

1
Prep the mushroom caps
- Twist out the stems from all 8 portobello caps and discard or save for another use.
- Wipe each cap clean with a damp paper towel.
- Use a spoon to gently scrape out the dark gills so the buns do not turn the burgers muddy and wet.
- Lay the caps gill-side up in a shallow dish or on a rimmed plate.
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Ready when: Caps are clean, gills removed, and the caps are in a single layer.
Tip: Scrape lightly. Pressing hard can tear the cap and leave a hole.
2
Marinate the caps
- In a small bowl, whisk 2 tbsp (30 ml) olive oil, 1 tbsp (15 ml) balsamic vinegar, 2 grated garlic cloves, ¼ tsp salt, and ¼ tsp pepper.
- Spoon it over the gill sides of the mushrooms, then brush any leftover mixture over the tops.
- Leave the caps gill-side up while you make the patties.
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Ready when: Every cap looks glossy and the garlic is spread across the gill sides.
Tip: Do not marinate longer than 45 minutes, or the mushrooms will release too much liquid.
3
Mix the patty mixture
- In a large bowl, combine 1½ lb (680 g) cold ground chicken, ¼ cup (28 g) almond flour, the beaten egg, 3 minced garlic cloves, the sliced scallions, 1 tsp smoked paprika, 1 tsp oregano, 1¼ tsp kosher salt, and ½ tsp pepper.
- Mix with your hands for about 30 seconds, just until the seasonings are evenly distributed and the mixture looks tacky.
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Ready when: No streaks of flour or spices remain, and the mixture holds together when squeezed.
Tip: Overmixing makes chicken patties rubbery, so stop as soon as it comes together.
4
Shape and chill patties
- Divide the mixture into 4 equal portions of about 6 oz (170 g) each.
- Wet your hands lightly with cold water to stop sticking.
- Shape each portion into a patty about 3½ inches (9 cm) wide and ¾ inch (2 cm) thick, pressing a shallow dimple into the center with your thumb.
- Place on a parchment-lined plate and refrigerate for 15 minutes so they firm up.
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Ready when: Patties feel firm and cold to the touch and keep their shape when lifted.
Tip: The dimple stops the center from puffing up, so the burgers stay flat enough to stack.
5
Make the garlic mayo
- In a small bowl, stir together ¼ cup (60 g) mayonnaise, the grated small garlic clove, 2 tsp lemon juice, and 1 tsp Dijon mustard until smooth.
- Cover and refrigerate until serving.
- Slice the tomato and red onion at this point if you have not already.
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Ready when: The sauce is smooth, pale, and has no visible lumps of garlic.
6
Preheat and oil the grillOven 450°F / 230°C
- Heat a gas or charcoal grill to medium-high, about 425–450°F (220–230°C), for 10 minutes.
- Scrape the grates clean with a grill brush.
- Fold a paper towel, dip it in 1 tbsp (15 ml) olive oil, grip it with tongs, and wipe it over the grates.
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Ready when: You can hold your hand 5 inches above the grates for only 3–4 seconds, and the grates look glossy.
Tip: Oiled hot grates are the best way to keep chicken from sticking.
7
Grill the mushroom buns
- Place the caps on the grill rounded-side down, gill-side up, and close the lid.
- Grill 4 minutes, then flip and grill gill-side down for another 3–4 minutes.
- Move to a platter, gill-side up, and leave the grill hot for the patties.
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Ready when: Caps are tender when pierced with a fork, have grill marks, and have released some juices but still hold their shape.
Tip: Drain any liquid pooled in the caps before assembling to avoid soggy burgers.
8
Grill the patties
- Place the chilled patties on the grill, dimple-side up, and close the lid.
- Cook 5–6 minutes without moving them, until they release easily from the grates.
- Flip once and cook another 5–6 minutes.
- Check the internal temperature with an instant-read thermometer in the side of the thickest patty.
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Ready when: Patties are golden brown with grill marks, juices run clear, and the thermometer reads 165°F (74°C).
Tip: Do not press the patties with a spatula; it squeezes out the juices.
9
Melt the provolone
- During the last minute of cooking, top each patty with a slice of provolone and close the lid.
- Cook for 1 minute, until the cheese is soft and melting at the edges.
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Ready when: The cheese is glossy and drooping over the edges of the patty.
Tip: Take the patties off the grill right after the cheese melts, so they do not overcook.
10
Rest and assemble
- Transfer the patties to a clean plate and rest for 3 minutes.
- Spread the garlic mayo on the gill side of 4 mushroom caps.
- Set a patty on each, then layer with tomato, red onion, and arugula.
- Top with the remaining 4 mushroom caps, gill-side down.
- Serve right away with napkins.
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Ready when: The burger stacks neatly and the top cap sits level.
Tip: Put the arugula between the patty and the tomato to keep the mushroom bun from getting soggy.

Good to know

Tips

Remove the stems and scrape the gills, so the mushroom buns are flat and do not release dark liquid onto the burger.
Cooking on medium-high heat chars the outside of the patty before the inside dries out. If flare-ups happen, move the patties to a cooler part of the grill.
No grill? Cook the mushrooms and patties in a large cast-iron skillet over medium-high heat, using the same times, and cover with a lid when melting the cheese.
Pat the cooked mushroom caps gently with a paper towel before assembling for a firmer bun.

Make ahead

"Shape the patties up to 1 day ahead, stack them with parchment between each, and refrigerate covered. Mix the garlic mayo up to 3 days ahead. Marinate and grill the mushroom caps up to 1 day ahead and reheat briefly on the grill or in a skillet."

Storage & reheating

"Assembled burgers do not store well. Store the cooked patties and mushroom caps separately in airtight containers in the fridge for up to 3 days. Freeze cooked patties for up to 2 months. Reheat patties in a covered skillet over medium-low heat for 4–5 minutes per side, or microwave for 1–2 minutes, until steaming hot (165°F/74°C). Reheat the mushroom caps in a skillet for 2 minutes per side. Do not leave cooked burgers at room temperature for more than 2 hours."

Substitutions

ground chicken (thigh or 93% lean) → Ground turkey (thigh meat or 93% lean). Cooks the same way; still cook to 165°F (74°C).
fine almond flour → Finely crushed pork rinds (about 3 tbsp / 20 g). Keeps the patties low-carb and helps hold moisture. Use almond flour for a nut-based option.
sliced provolone cheese → Swiss, mozzarella, or pepper jack cheese. Use any good melting cheese in slices.
balsamic vinegar → Red wine vinegar or Worcestershire sauce. Red wine vinegar is sharper, so use ½ tbsp; Worcestershire adds a deeper, savory flavor.