Combine beans, green onions, garlic, parsley, cilantro, lemon juice, cumin, baking powder, red pepper flakes, salt and pepper to taste in a food processor; pulse until mixture is coarsely chopped and beginning to come together.
Form mixture into 8 golf ball-sized rounds. Place on a greased baking sheet; press to slightly flatten. Bake until crispy and light gold, about 18 minutes. Place baking sheet on a wire rack.
While falafel bakes, heat a dry skillet over medium-high heat. Warm pita bread in batches, about 1 minute per side. Transfer to paper towels.
Spread each round of pita with 2 tablespoons hummus; top with two falafel rounds. Top with 1 tablespoon tabbouleh and 1 tablespoon lettuce. Top with 1 tablespoon kalamata olives, a dash of hot sauce, tomatoes and cucumbers. Fold like a taco to eat.