1. Preheat oven to 425°.
2. Place beans in a large bowl; lightly mash. Stir in onion and next 7 ingredients. Divide mixture into 4 portions; shape each into a 1/2-inch-thick patty.
3. Arrange patties on a baking sheet coated with cooking spray. Bake at 425° for 8 minutes; turn after 6 minutes. Add bun halves to pan; bake 3 minutes.
4. Combine mayonnaise, Sriracha, and juice; spread over bottom halves of buns. Top each serving with 1 patty, 1/2 cup arugula, and top halves of buns.