Rinse the dry lentils. Place the lentils in a small to medium saucepan and cover with 2 cups of water or vegetable broth; add ½ teaspoon salt. Bring to a boil over medium heat. Once boiling, reduce heat to low to keep simmering and cover loosely. Cook lentils for around 20 - 25 minutes, until lentils are soft but not falling apart. If they are not done at this point, check every 5 minutes until done. Strain in a colander and let cool on a baking sheet. Reserve excess lentils for another use.
To make flax egg, combine ground flaxseed meal with ⅓ cup hot water. Stir with a and let sit for 10 to 15 minutes until it thickens.
Chop garlic in the food processor. Add onion chunks and pulse for 15 times until chopped.
Place the cooled lentils, cooked or canned black beans, rolled oats, psyllium husk powder, chili powder, smoked paprika, black pepper, and remaining sea salt in the food processor bowl. Pulse several times until it comes together.
Add the oat flour, flaxseed mixture, carrot, sunflower seeds, and diced parsley. Pulse a few times until just combined. Turn into a bowl and combine thoroughly with a spatula or spoon. The mixture should hold together easily when you pinch it with your fingers. Taste and adjust the salt and seasonings as needed.
Form 8 to 10 patties with your hands. Scoop with ½-cup measuring cup; each patty is approximately 3.5 oz.
Heat a cast-iron pan or non-stick skillet over medium heat. Once hot, add the grapeseed oil. Cook the burgers for 4 to 5 minutes until browned. Once brown, flip and cook for another 3 to 4 minutes until browned.
Serve immediately with vegan burger buns, lettuce, sliced tomato, and your favorite toppings.
Notes
Note: Drain and rinse canned lentils and canned black beans. If using precooked lentils, use 1 ⅔ cup.
You can bake these burgers at 375°F for 15 minutes on one side, then flip them over and bake for another 15 minutes or so, until they are browned.
Burgers can be refrigerated for 3 days or frozen up to 3 months, cooked or uncooked. Reheating method is the same as the cooking method on the stovetop.
You can cook these patties on a stovetop grill pan, and follow the same instructions. If you want to cook these lentil black bean burgers on a grill outside, it should be fine since these burgers hold together well.