Rinse 1 cup of red lentils under cold water. In a pot, combine with 3 cups of water, bring to a boil, then simmer for about 15 minutes until tender. Drain excess water and set aside.
In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add minced garlic, chopped onion, and green bell pepper, and sauté for about 5-7 minutes until soft.
Add cooked lentils, drained black beans, and chopped green onions to the skillet. Stir to combine.
Sprinkle in 2 tablespoons of chili powder and 2 teaspoons of smoked paprika. Pour in the canned tomato sauce and chili sauce, stirring until evenly coated.
Add 3 tablespoons of maple syrup and 2 tablespoons of low-sodium soy sauce. Stir well and let simmer for about 5 minutes.
Spoon the mixture onto whole wheat hamburger buns and serve immediately while warm, garnished with additional green onions if desired.
