Rinse the lentils and pick out any hard pieces then combine them in a saucepan with 2 cups water. Bring to low boil and cook for 30 minutes, until tender. Cooking time may vary depending on how old the lentils are. Drain off any excess liquid and set aside to cool.

In a small bowl, combine 3/4 cup mayo, zest and juice of 1 lemon and chopped basil leaves. Stir together, cover and store in the refrigerator.

In a large skillet, warm 2 tablespoons olive oil over medium heat. Using a food processor, finely chop the shallot then add it to the skillet and cook until translucent. Finely chop the mushrooms and garlic then add them to skillet along with 1 teaspoon salt and 1/2 teaspoon pepper. Cook for about 7 minutes, until the mushrooms are soft, then remove from the heat and set aside to cool.

Add the peas and 3/4 cup of the cooked lentils to the bowl of the food processor and pulse until finely chopped. You should be able to press the mixture together with your fingers and have it hold together.

In a large bowl, combine the cooked mushrooms, lentil pea mixture, remaining cooked lentils and 1/2 cup cornmeal then stir together. Next add 2 tablespoons of the lemon basil mayo and 1/2 cup chickpea flour. Stir together until well-combined. Transfer to the refrigerator and allow to set for 30 minutes while you clean the kitchen.

Line a baking sheet with parchment paper then spread 1/4 cup cornmeal along the bottom. Remove the lentil pea mixture from the refrigerator then scoop out roughly 1/4 cup at a time and use your hands to form into separate patties. Place them on the baking sheet then sprinkle the remaining cornmeal on top.

Wipe out the same large skillet you used to cook the mushrooms then add one tablespoon olive oil over medium heat. Using a spatula, carefully transfer the burgers one at a time to the skillet. Cook for about 5 minutes on each side until a light golden crust forms.

Serve warm on toasted buns with lemon basil mayo, sliced red onion, tomato and lettuce. Leftovers can be stored in an airtight container for up to 4 days or frozen for up to one month.