Grass-Fed Beef Burgers with Sweet Potato Buns

Name: Grass-Fed Beef Burgers with Sweet Potato Buns
Prep time: 30 min
Cook time: 26 min
Total time: 56 min
Yield: 4 servings
Cuisine: American
Ingredients: 3 large (about 14 oz each) (1200 g) large sweet potatoes, scrubbed, skin on, ends trimmed, cut crosswise into ½-inch (1.25 cm) thick rounds; keep the 8 widest, most even rounds; 1½ tbsp (22 ml) extra-virgin olive oil; ½ tsp (3 g) kosher salt; ½ tsp (1 g) smoked paprika; 1½ lb (680 g) grass-fed ground beef, 85% lean, cold, straight from the refrigerator; 1 tbsp (15 ml) Worcestershire sauce; 1½ tsp (9 g) kosher salt; ½ tsp (1 g) black pepper, freshly ground; 3 tbsp (45 g) plain whole-milk Greek yogurt; 1 tbsp (15 g) Dijon mustard; 1 tbsp (15 g) whole-grain mustard; 1 tsp (5 ml) fresh lemon juice; 1 tsp (7 g) honey; 2 cups, loosely packed (60 g) baby arugula, washed and dried; ½ small (50 g) red onion, sliced into thin rings; 1 medium (150 g) ripe tomato, cut into 4 thin slices

From the MyKitchenBank Kitchen

Juicy oven-baked grass-fed beef patties stacked between caramelized sweet potato rounds, with peppery arugula and a tangy two-mustard yogurt sauce. Everything bakes on sheet pans, so there's no grill and no bread.

Prep: 30 min
Cook: 26 min
Wait: 5 min
Total: 1 hr 1 min
Makes: 4 burgers (8 sweet potato bun rounds)

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Ingredients

4 servings

For the sweet potato buns
3 large (about 14 oz each) (1200 g) large sweet potatoes, scrubbed, skin on, ends trimmed, cut crosswise into ½-inch (1.25 cm) thick rounds; keep the 8 widest, most even rounds
1½ tbsp (22 ml) extra-virgin olive oil
½ tsp (3 g) kosher salt
½ tsp (1 g) smoked paprika
For the burgers
1½ lb (680 g) grass-fed ground beef, 85% lean, cold, straight from the refrigerator
1 tbsp (15 ml) Worcestershire sauce
1½ tsp (9 g) kosher salt
½ tsp (1 g) black pepper, freshly ground
For the mustard sauce
3 tbsp (45 g) plain whole-milk Greek yogurt
1 tbsp (15 g) Dijon mustard
1 tbsp (15 g) whole-grain mustard
1 tsp (5 ml) fresh lemon juice
1 tsp (7 g) honey
To assemble
2 cups, loosely packed (60 g) baby arugula, washed and dried
½ small (50 g) red onion, sliced into thin rings
1 medium (150 g) ripe tomato, cut into 4 thin slices

Equipment (8)

2 rimmed baking sheets, 18×13-inch (46×33 cm)
Parchment paper
Oven-safe wire rack that fits inside one baking sheet (optional but helpful)
Sharp chef's knife
Instant-read thermometer
Small mixing bowl
Large mixing bowl
Thin metal spatula

Steps

Before you start

Choose wide, evenly shaped sweet potatoes, about 3 inches (7.5 cm) across at the thickest part, so the rounds are burger-sized.
Keep the beef refrigerated until you shape the patties. Cold meat holds together better and stays juicier.
Place one oven rack in the upper third and one in the lower third, then preheat the oven to 425°F (220°C).
You will need an instant-read thermometer. Grass-fed beef is lean and goes from juicy to dry quickly, so check the temperature rather than guessing.

1
Preheat and slice potatoesOven 425°F / 220°C
- Position oven racks in the upper and lower thirds and preheat to 425°F (220°C).
- Line one baking sheet with parchment.
- Trim the ends off each sweet potato, then cut crosswise into ½-inch (1.25 cm) thick rounds.
- Choose the 8 widest, most even rounds for buns.
- Save the smaller end pieces for another meal.
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Ready when: Rounds are uniform in thickness, about ½ inch (1.25 cm), so they cook evenly.
Tip: Use a ruler on the first cut. Slices thinner than ½ inch turn dry and brittle, and thicker ones stay hard in the center.
2
Season the bun rounds
- In a large bowl, toss the 8 sweet potato rounds with the olive oil, ½ tsp salt and smoked paprika until every round is lightly and evenly coated.
- Arrange them in a single layer on the parchment-lined sheet with space between them.
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Ready when: All rounds are glossy with oil and none overlap.
3
Roast bun roundsOven 425°F / 220°C
- Slide the sheet onto the upper rack of the 425°F (220°C) oven.
- Roast for 12 minutes, until the undersides are starting to turn golden.
- Use this time to shape the patties and make the sauce.
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Ready when: Undersides are golden at the edges when lifted with a spatula.
4
Shape the patties
- Place the cold beef in a large bowl.
- Sprinkle with 1½ tsp salt, the pepper and Worcestershire sauce.
- Mix gently with your fingertips just until combined, about 20 seconds.
- Divide into 4 equal portions of about 6 oz (170 g) each.
- Shape each into a patty about 4 inches (10 cm) wide and ¾ inch (2 cm) thick, then press a shallow dimple in the center with your thumb.
- Place on a second baking sheet, ideally set with a wire rack, and refrigerate until the buns are ready.
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Ready when: Patties are evenly sized with smooth edges and a dimpled center.
Tip: Overmixing makes lean grass-fed beef dense and tough. Stop as soon as the seasoning is distributed.
5
Mix mustard sauce
- In a small bowl, stir together the Greek yogurt, Dijon, whole-grain mustard, lemon juice and honey until smooth.
- Taste and add a pinch of salt if you like.
- Refrigerate until serving.
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Ready when: Sauce is smooth, pale golden and spreadable.
6
Prep toppings
- Slice the red onion into thin rings and the tomato into 4 thin slices.
- Keep the washed, dried arugula in a bowl so it is ready to pile on.
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Tip: Dry the arugula well so it doesn't make the buns soggy.
7
Flip buns, bake burgersOven 425°F / 220°C
- Pull the potato sheet out when the 12 minutes are up.
- Flip each round with a thin spatula and return the sheet to the upper rack.
- Put the patty sheet on the lower rack at the same time.
- Bake both for 14 minutes at 425°F (220°C).
- Insert a thermometer sideways into the center of a patty.
- It should read 160°F (71°C).
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Ready when: Patties read 160°F (71°C) in the center with no pink raw meat; potato rounds are tender when pierced with a knife and browned at the edges.
Tip: If the patties are done before the potatoes, remove them and let the potatoes finish. If the potatoes are done first, pull them and keep the patties baking.
8
Rest burgers
- Move the patties to a clean plate and let them rest for 5 minutes so the juices settle.
- Leave the sweet potato rounds on the hot sheet to firm up slightly.
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Ready when: Juices stop pooling when a patty is nudged; potato rounds hold their shape when lifted.
Tip: Cutting or pressing the patties now would let the juices run out.
9
Assemble and serve
- For each burger, spread 1 tbsp mustard sauce on a sweet potato round (bottom bun), then add a tomato slice, a patty, a few onion rings and a handful of arugula.
- Spread another round with sauce and set it on top.
- Serve right away with extra sauce for dipping.
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Ready when: Burgers stand upright and the buns stay intact when picked up.
Tip: Eat these while warm. The sweet potato rounds are softer than bread, so a knife and fork is fine.

Good to know

Tips

Grass-fed beef is leaner and cooks faster than conventional beef, so start checking the temperature at 12 minutes.
Don't crowd the sweet potato rounds. Space lets them roast and brown rather than steam.
The dimple in each patty stops the center from puffing up, so the burger stays flat and stacks neatly.
Cut the rounds from the thick middle of each potato for the widest, sturdiest buns.

Make ahead

"Slice the sweet potatoes up to 8 hours ahead and keep them submerged in cold water in the refrigerator; drain and dry them thoroughly before oiling. Mix the mustard sauce up to 3 days ahead. Shape the patties up to 1 day ahead, cover and refrigerate."

Storage & reheating

"Room temperature: no more than 2 hours. Refrigerator: store patties and sweet potato buns separately in airtight containers for up to 3 days; keep the sauce and greens separate. Freezer: cooked patties freeze for up to 2 months; wrap individually. Reheat patties in a 350°F (175°C) oven for 10 minutes, or until hot throughout (165°F / 74°C). Reheat buns on a sheet at 400°F (200°C) for 5–7 minutes."

Substitutions

grass-fed ground beef, 85% lean → Ground bison or ground turkey. Bison cooks the same way but dries out faster, so check at 12 minutes. Ground turkey must reach 165°F (74°C).
plain whole-milk Greek yogurt → Mayonnaise or dairy-free coconut yogurt. Mayonnaise gives a richer sauce; coconut yogurt keeps it dairy-free and adds a mild sweetness.
baby arugula → Baby spinach or butter lettuce. Milder flavor and slightly softer texture than arugula.
honey → Maple syrup. Use the same amount; it makes the sauce vegan-friendly if paired with dairy-free yogurt.