How to Make It
Process beans, oats, garlic, soy sauce, and chili powder in a food processor until ingredients begin to come together, about 30 seconds. Transfer bean mixture to a large bowl; stir in scallions. Shape mixture into 4 (¾ cup) patties. Let patties stand at room temperature 5 minutes, or refrigerate up to 3 hours.
Heat oil in a large nonstick skillet over medium-high. Cook patties in hot oil until browned, about 5 minutes per side. Place 1 patty on each hamburger bun bottom, and top each with ¼ cup salsa. Add lettuce, tomato slices, and red onion slices, and cover with bun tops.