01 -  In a small bowl, mix the ground flaxseed with water and let stand for 5 minutes until thickened. 
 02 -  In a large bowl, combine chickpeas, lentils, quinoa, finely diced onion, minced garlic, grated carrot, rolled oats, chopped parsley, smoked paprika, ground cumin, salt, and black pepper. 
 03 -  Add the prepared flax egg and olive oil to the mixture. Using a potato masher or fork, mash ingredients until they bind but still maintain some texture. 
 04 -  Divide mixture evenly and form into 4 patties, each about 1 inch thick. 
 05 -  Heat a non-stick skillet or grill pan over medium heat. Lightly oil the surface if needed. Cook patties 4 to 5 minutes per side until golden and crisp. 
 06 -  Lightly toast the burger buns just before serving. 
 07 -  Spread vegan mayonnaise or plant-based aioli on the bottom half of each bun. Add baby spinach or lettuce, a veggie patty, sliced tomato, avocado, sliced red onion, and additional toppings if desired. Cover with the top half of the bun. 
 08 -  Serve the assembled burgers hot with your chosen side.