These burgers are meaty without the use of plant-based meats. Lentils, mushrooms, and walnuts give them a dense texture and garlic, tamari, and apple cider vinegar adds flavor. The quick-pickled onions are tangy and will probably be your new favorite veggie burger garnish, especially when paired with the grainy, mustardy sauce made from sunflower seeds. Serve these on toasted buns with sweet potato fries and save this recipe for future use.
Lentil, Mushroom, and Walnut Burgers [Vegan, Gluten-Free]
For the Burgers:
- 14 ounces or 5 cups mixed mushrooms, cleaned, woody stems removed and thinly sliced
- 1-2 tablespoons extra virgin olive oil
- 3 cloves garlic, minced
- 2 1/2 tablespoons tamari
- 2 tablespoons apple cider vinegar
- 1 cup walnuts
- 2 tablespoons flax seeds
- 1/3 cup gluten-free rolled oats
- 1 cup cooked green De Puy lentils
- 1/4 cup flat leaf parsley
For the Quick-Pickled Onions:
- 1 medium red onion, very thinly sliced
- 1/3 cup apple cider vinegar
- 1/2 cup water
- 2 tablespoons maple syrup
For the Grainy Mustard Aioli:
- 1/2 cup raw sunflower seeds, soaked overnight
- 1 tablespoon apple cider vinegar
- 5 tablespoons olive oil
- 1 tablespoon grainy mustard
- 1/2 teaspoon fine grain sea salt
- 2 tablespoon water, or more as needed
- Toasted buns, radishes, chives, and greens for garnish.
To Make the Burgers:
- Add olive oil to a large non-stick skillet over medium heat. Add mushrooms and garlic and cook down until soft and tender and reduced significantly in size, about 12-15 minutes.
- Stir in apple cider vinegar and tamari and cook for another minute or two, scraping any sticky bits on the bottom of the pan and coating the mushrooms. Remove from heat and set aside.
- Add the walnuts, flax seeds, and oats to the bowl of a food processor and pulse until finely ground, then transfer to a large mixing bowl. Add the cooked mushrooms, lentils, and parsley to the bowl of the food processor and pulse until combined, breaking up any large bits of mushrooms or lentils.
- Add mushroom-lentil mixture to dry mixture and fold to combine. Press mixture into the bottom of the bowl gently with the palm of your hand and place in the fridge to set for at least 30 minutes, or overnight.
- Preheat oven to 400°F and line a rimmed baking sheet with parchment. Separate burger mixture into 6 equal parts and shape into patties.
- Place on parchment and brush the tops with olive oil. Bake in the oven for 10-12 minutes, then flip and brush the opposite side with oil.
- Return to oven and bake for another 10 minutes, or until crisp and firm. Remove and let cool slightly before serving.
- Cooked burgers can be kept in the fridge for a few days and reheated for a quick and easy dinner, or frozen for future burger nights.
To Make the Quick-Pickled Onions:
- Place vinegar, apple cider, and maple syrup in a small sauce pot and bring to a boil. Remove from heat and add onions. Make sure onions are well covered. Allow onions to "pickle" for at least 30 minutes or overnight. Keep in the refrigerator in a sealed jar for up to one week.
To Make the Grainy Mustard Aioli:
- Rinse and drain sunflower seeds. Place seeds, apple cider vinegar, olive oil, mustard, and salt into the bowl of a food processor and blend until smooth, scraping down the edges and adding water as needed to help thin.
- Depending on the power of your blender this can take up to 10 minutes for an ultimate smooth consistency. Keep aioli in a sealed container in the refrigerator for a few days.
To Assemble the Burgers:
- Toast buns. Place warm burger on the bottom bun, pile high with pickled onions, sliced radishes, greens, chives, and cracked black pepper.
- Slather on the aioli and serve.