Ingredients
Equipment
Method
Make the Patties
- Stir the ground flaxseed and warm water together. Let stand for 10 minutes, until thickened.
- Toast the oats and walnuts in a dry skillet over medium heat for 3–4 minutes, stirring often. Let cool, then pulse in a food processor to coarse crumbs, not flour.
- Heat 1 tablespoon oil in a large skillet over medium-high heat. Add the 1 cup chopped mushrooms and 1/2 cup onion and cook for 7–9 minutes, until their water has evaporated and the vegetables begin to brown. Add the garlic and cook for 30–60 seconds.
- Pulse the lentils and beans briefly so some pieces break down while plenty of texture remains. Transfer to a bowl with the cooked mushroom mixture, oat-walnut crumbs, flax binder, tamari, tomato paste, nutritional yeast, smoked paprika, onion powder, black pepper and salt.
- Mix and press the mixture together until it holds when squeezed. Let stand for 10 minutes. Divide into 6 patties about 3/4 inch thick. For easier handling, chill for 15–20 minutes.
Make the Duxelles
- Heat the olive oil in a wide skillet over medium heat. Cook the onion for 4–5 minutes, until translucent. Add the garlic and cook for 30 seconds.
- Add the finely chopped mushrooms, salt and pepper. Cook for 12–15 minutes, stirring occasionally, until the released liquid has evaporated and the mushrooms are deeply browned and almost spreadable.
- Stir the tamari and miso into the mushrooms, then add the nutritional yeast and cook for 1–2 minutes. Remove from the heat and stir in 1 teaspoon truffle oil. Taste before adding the remaining truffle oil or more salt.
Make the Sauce
- Blend the soaked cashews, water, lemon juice, miso, tamari, rice vinegar, maple syrup, red pepper flakes, ginger and sesame seeds until completely smooth. Add more water 1 tablespoon at a time only if needed; keep the sauce thick and spoonable.
Make the Tomato Topping
- Combine the sun-dried tomatoes, water, balsamic vinegar, olive oil, maple syrup and salt in a small saucepan. Simmer over low heat for 4–6 minutes, until the tomatoes are tender and glossy.
Cook and Assemble
- Lightly oil a cast-iron or other heavy skillet and heat it over medium to medium-high. Add the chilled patties and cook undisturbed for 4–5 minutes, until a firm browned crust forms. Work in batches if needed.
- Carefully flip the patties and cook for 4–5 minutes more. Do not press or move them unnecessarily. If the patties are especially thick or cold, lower the heat and cook for 1–2 minutes longer, until firm and hot through.
- Toast the cut sides of the buns in the skillet for 1–2 minutes, until lightly golden.
- Layer each bottom bun with sauce, optional arugula, a patty, mushroom duxelles, warm sun-dried tomatoes and optional red onion. Add a little more sauce and the top bun. Serve immediately.
Nutrition
Notes
Success Tips: Drain the lentils and beans extremely well; after rinsing, blot them with a clean towel if needed. Pulse rather than puree so the patties keep visible texture. If the mixture feels wet, add certified gluten-free oats 1 tablespoon at a time. If it feels dry or cracks, mix in water 1 teaspoon at a time. Chill the shaped patties for 15–20 minutes; 30–60 minutes makes them firmer.
Duxelles: Chop the mushrooms very finely and use a wide pan so moisture can escape. Continue cooking for up to 18 minutes if needed. Add truffle oil only after removing the pan from the heat. Up to half of the mushrooms may be shiitakes for deeper flavor; portobellos work but may need longer evaporation.
Sauce: Soak cashews in cool water for several hours or cover with very hot water for 20–30 minutes, then drain. Thin only 1 tablespoon at a time and keep the sauce thick enough to stay on the burger.
Swaps: Raw sunflower seeds can replace the walnuts. Cannellini beans make a creamier patty; chickpeas make it slightly firmer. For a soy-free variation, use a verified gluten-free, soy-free savory seasoning and chickpea miso, checking every package label.
Make Ahead and Storage: Shape and refrigerate uncooked patties for up to 2 days. Refrigerate the duxelles for up to 3 days and the sauce for up to 4 days. Store components separately and assemble just before serving. Reheat patties gently in a skillet; add a splash of water to the duxelles if needed and whisk a little water into chilled sauce.
Air Fryer: Preheat to 375°F. Lightly brush chilled patties with oil and arrange in one layer. Air fry for 12–15 minutes, flipping after 6–7 minutes; add 2–3 minutes for especially thick or cold patties. Use firmness and surface browning, not time alone, as the doneness cue.
Serving Ideas: Serve with roasted potato wedges, sweet potato fries, an arugula salad, vinegar-based cabbage slaw, roasted asparagus or grilled vegetables. For an open-faced version, use one toasted bun half. Leftover patties work in bowls, over greens or grains, or crumbled over roasted potatoes.
