In small bowl, mix ground flaxseeds with 2-1/2 tablespoons water. Let sit for 5 minutes to thicken.

In skillet over medium heat, sauté onion, garlic and mushrooms until softened (about 5–7 minutes). Remove from heat.

In food processor, pulse walnuts until finely chopped (but not a paste). Add sautéed veggies, black beans, brown rice, soy sauce, liquid smoke and flax egg. Pulse until combined but still slightly chunky.

Transfer mixture to bowl. Stir in breadcrumbs, nutritional yeast, Italian seasoning, smoked paprika, salt and pepper. Mix until fully combined. If too wet, add more breadcrumbs; if too dry, add splash of water.

Form into 4–6 burger patties. Refrigerate for 15–30 minutes to help them firm up.

Cook on greased grill or skillet over medium heat for 4–5 minutes per side, until golden and heated through.

Load up on buns, toppings, and sauces.