Vegan Lentil Walnut Burgers with Cashew Aioli

Name: Vegan Lentil Walnut Burgers with Cashew Aioli
Prep time: 40 min
Cook time: 55 min
Total time: 1 h 35 min
Yield: 6 servings
Cuisine: American
Ingredients: 1 cup (200 g) dry brown or green lentils, rinsed and picked over; 2½ cups (600 ml) water, for cooking the lentils; 1 cup (100 g) walnut halves, toasted and cooled; 2 tbsp (30 ml) olive oil; 1 medium (about 5 oz) (150 g) yellow onion, finely diced; 1 medium (about 3 oz) (80 g) carrot, peeled and coarsely grated; 8 oz (225 g) cremini mushrooms, very finely chopped (about the size of rice grains); 3 cloves (9 g) garlic cloves, minced; 1 tbsp (16 g) tomato paste; 1 tsp (2½ g) smoked paprika; 1 tsp (2 g) ground cumin; 1 tbsp (15 ml) soy sauce or tamari; 2 tbsp (14 g) ground flaxseed; 5 tbsp (75 ml) cold water, for the flax gel; ¾ cup (70 g) old-fashioned rolled oats; ¼ cup (15 g) fresh flat-leaf parsley, finely chopped; 1 tsp (6 g) fine sea salt; black pepper, freshly ground, to taste; ½ cup (70 g) raw unsalted cashews, soaked in boiling water for 15 minutes, then drained; 1 small clove (3 g) garlic clove, peeled; 2 tbsp (30 ml) fresh lemon juice; 3 tbsp (45 ml) cold water, plus more as needed; 1 tsp (5 g) Dijon mustard; ¼ tsp (1½ g) fine sea salt; 6 buns (360 g) vegan burger buns, split; 6 large leaves (60 g) butter lettuce leaves, washed and dried; 2 medium (300 g) ripe tomato, cut into 6 thick slices; ½ small (50 g) red onion, thinly sliced (optional)

From the MyKitchenBank Kitchen

Hearty baked burgers with tender lentils, toasted walnuts, mushrooms and smoked paprika, served with a creamy garlic-lemon cashew aioli. Fully plant-based, with no chicken, and firm enough to hold in a bun.

Prep: 40 min
Cook: 55 min
Wait: 30 min
Total: 2 hr 5 min
Makes: 6 burgers (about ¾ cup / 150 g of mixture each), plus about 3/4 cup (180 ml) aioli

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Ingredients

6 servings

For the burgers
1 cup (200 g) dry brown or green lentils, rinsed and picked over
2½ cups (600 ml) water, for cooking the lentils
1 cup (100 g) walnut halves, toasted and cooled
2 tbsp (30 ml) olive oil
1 medium (about 5 oz) (150 g) yellow onion, finely diced
1 medium (about 3 oz) (80 g) carrot, peeled and coarsely grated
8 oz (225 g) cremini mushrooms, very finely chopped (about the size of rice grains)
3 cloves (9 g) garlic cloves, minced
1 tbsp (16 g) tomato paste
1 tsp (2.5 g) smoked paprika
1 tsp (2 g) ground cumin
1 tbsp (15 ml) soy sauce or tamari
2 tbsp (14 g) ground flaxseed
5 tbsp (75 ml) cold water, for the flax gel
¾ cup (70 g) old-fashioned rolled oats
¼ cup (15 g) fresh flat-leaf parsley, finely chopped
1 tsp (6 g) fine sea salt
black pepper, freshly ground, to taste
For the cashew aioli
½ cup (70 g) raw unsalted cashews, soaked in boiling water for 15 minutes, then drained
1 small clove (3 g) garlic clove, peeled
2 tbsp (30 ml) fresh lemon juice
3 tbsp (45 ml) cold water, plus more as needed
1 tsp (5 g) Dijon mustard
¼ tsp (1.5 g) fine sea salt
To serve
6 buns (360 g) vegan burger buns, split
6 large leaves (60 g) butter lettuce leaves, washed and dried
2 medium (300 g) ripe tomato, cut into 6 thick slices
½ small (50 g) red onion, thinly sliced (optional)

Equipment (10)

Large rimmed baking sheet (18×13-inch / 46×33 cm)
Parchment paper
Medium saucepan with lid (3-quart / 3 L)
Large skillet, 12-inch (30 cm)
Food processor
Blender (high-speed preferred)
Large mixing bowl
Fine-mesh sieve
Spatula (thin metal or fish spatula)
Instant-read thermometer (optional)

Steps

Before you start

Read the whole recipe first. The lentils simmer while you sauté the vegetables and make the aioli, so you can work on all three at once.
Use brown or green lentils. Red lentils collapse into mush and make the patties pasty.
Line a large rimmed baking sheet with parchment paper before you start.
You need a high-speed blender for a smooth aioli. With a regular blender, soak the cashews for 2 hours in hot tap water instead.

1
Toast nuts, soak cashewsOven 350°F / 175°C
- Heat the oven to 350°F (175°C).
- Spread the walnuts on the baking sheet and toast for 8 minutes, until fragrant and a shade darker.
- Tip them onto a plate to cool.
- Meanwhile, put the cashews in a heatproof bowl, cover with boiling water and let them soak for 15 minutes.
- Leave the oven on for now.
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Ready when: Walnuts smell nutty and look lightly golden; cashews are soft enough to squash between your fingers
Tip: Walnuts burn quickly and turn bitter. Pull them as soon as you smell them.
2
Simmer the lentils
- Combine the lentils and 2½ cups (600 ml) water in the medium saucepan.
- Bring to a boil over high heat, then reduce to medium-low, cover partly and simmer for 22–25 minutes.
- In a small bowl, stir the ground flaxseed into 5 tbsp (75 ml) cold water and set aside to thicken into a gel.
- Do the next step while the lentils simmer.
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Ready when: Lentils are completely tender with no chalky center, and most water is absorbed. Some will be slightly split.
Tip: Do not salt the water. Salt can keep lentil skins tough.
3
Sauté the vegetables
- Heat the olive oil in the large skillet over medium-high heat.
- Add the onion and carrot and cook, stirring often, for 4 minutes until the onion is soft.
- Add the mushrooms and cook 6–8 minutes more, stirring, until they release their liquid and it fully evaporates and the pan looks dry.
- Stir in the garlic, tomato paste, smoked paprika and cumin and cook 1 minute until the paste darkens slightly.
- Add the soy sauce, scrape up any browned bits, and remove from the heat.
- Scrape into your large mixing bowl and let cool for 5 minutes.
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Ready when: No liquid is left in the pan and the mushrooms look browned and slightly sticky
Tip: Wet mushrooms are the number one cause of soft, crumbly burgers, so cook off all the moisture.
4
Blend the aioli
- Drain the soaked cashews and add them to the blender with the garlic clove, lemon juice, 3 tbsp (45 ml) cold water, Dijon and ¼ tsp salt.
- Blend on high for 1–2 minutes, scraping down the sides once, until completely smooth and creamy.
- If it is thicker than mayonnaise, blend in more water 1 tsp at a time.
- Taste and adjust salt or lemon.
- Transfer to a small bowl, cover and refrigerate.
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Ready when: Silky with no gritty bits; it falls from a spoon in a thick ribbon
Tip: It thickens in the fridge, so make it slightly looser than you want it.
5
Mix the burger mixture
- Drain the cooked lentils very well in the sieve, shaking out water, then let them steam-dry for 2 minutes.
- Add 1½ cups (about 300 g) of the lentils to the food processor with the cooled walnuts and pulse 6–8 times until the walnuts are in small crumbs and the lentils are roughly mashed.
- Scrape into the bowl with the vegetables.
- Add the remaining whole lentils, the oats, flax gel, parsley, 1 tsp salt and several grinds of pepper.
- Mix firmly with a spatula or your hands for 1 minute.
- Let the mixture sit for 10 minutes so the oats absorb moisture.
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Ready when: A scoop pressed in your palm holds together without cracking, and is moist but not wet
Tip: Do not purée it. A coarse, varied texture gives the burgers a meaty bite.
6
Shape the pattiesOven 400°F / 205°C
- Heat the oven to 400°F (200°C) and line the baking sheet with fresh parchment.
- Divide the mixture into 6 equal portions of about ¾ cup (150 g).
- Pack each firmly and press into a patty about 4 inches (10 cm) wide and ¾ inch (2 cm) thick, smoothing the edges so they don't crack.
- Place them 1 inch (2.5 cm) apart on the sheet.
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Ready when: Patties have smooth edges and hold their shape when lifted with a spatula
Tip: If the mix sticks to your hands, wet them lightly. If it feels too wet to hold, stir in 1–2 tbsp more oats.
7
Bake and flipOven 400°F / 205°C
- Bake the patties on the middle rack for 15 minutes.
- Carefully flip each with a thin spatula and bake 12–15 minutes more.
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Ready when: Both sides are browned and the edges look dry and slightly crisp; the center feels firm when pressed
Tip: Flip gently and only once. They are fragile until the second side sets.
8
Rest and toast bunsOven 400°F / 205°C
- Remove the patties from the oven and let them rest on the pan for 5 minutes so they firm up.
- While they rest, place the buns cut-side up on a second tray or directly on the oven rack and toast at 400°F (200°C) for 2–3 minutes, until lightly golden.
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Ready when: Patties hold together when nudged; bun edges are golden
9
Assemble and serve
- Spread a generous spoonful of cashew aioli on both halves of each toasted bun.
- Layer the bottom bun with lettuce, a burger, a tomato slice and red onion if using.
- Add extra aioli, close the bun and serve right away.
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Tip: Put the lettuce against the bottom bun to keep it from going soggy.

Good to know

Tips

Dry mixture, not wet: drain the lentils well and cook off all mushroom moisture. That is what keeps the patties from crumbling.
Chill shaped patties for 20 minutes before baking if your kitchen is warm. This makes them easier to flip.
Pulse only part of the lentils so you get both a binding paste and whole lentils for texture.
These are baked, not fried, so they won't crust heavily. For extra crispness, brush the tops lightly with olive oil before baking.

Make ahead

"Shape the raw patties up to 24 hours ahead, separate with parchment, and refrigerate covered, then add 2–3 minutes to the bake time. The aioli keeps for up to 5 days, and the cooked lentils can be made 2 days ahead."

Storage & reheating

"Cooked patties keep at room temperature up to 2 hours, in an airtight container in the fridge up to 4 days, or frozen up to 3 months (freeze on a tray, then bag, with parchment between). Reheat from fridge on a baking sheet at 375°F (190°C) for 10–12 minutes, or from frozen for 18–20 minutes, until hot throughout. Keep the aioli in a sealed jar in the fridge for up to 5 days; stir in a splash of water if it thickens."

Substitutions

walnut halves → pecans or sunflower seeds. Toast the same way. Sunflower seeds make the burgers nut-free but slightly milder in flavor.
old-fashioned rolled oats → plain dry breadcrumbs or gluten-free oats. Use ¾ cup (80 g) breadcrumbs, or certified gluten-free oats, and gluten-free buns and tamari for a gluten-free burger.
raw unsalted cashews → raw sunflower seeds or store-bought vegan mayonnaise. Sunflower seeds need the same soak. Vegan mayo (½ cup / 115 g) mixed with the garlic, lemon and Dijon works as a shortcut.
ground flaxseed → chickpea flour slurry. Whisk 3 tbsp (24 g) chickpea flour with 3 tbsp (45 ml) water in place of the flax gel.