Mushroom Quinoa Veggie Burgers with Special Sauce

Name: Mushroom-Quinoa Veggie Burgers with Special Sauce
Ingredients: 1 large portobello mushroom, gills removed, roughly chopped; 1 cup no-salt-added canned black beans, rinsed; 2 tablespoons unsalted creamy almond butter; 3 tablespoons canola mayonnaise, divided; 1 teaspoon ground pepper; ¾ teaspoon smoked paprika; ¾ teaspoon garlic powder, divided; ½ teaspoon salt; ½ cup cooked quinoa; ¼ cup old-fashioned rolled oats; 1 tablespoon ketchup; 1 teaspoon Dijon mustard; 1 tablespoon extra-virgin olive oil; 4 whole-wheat hamburger buns, toasted; 2 leaves green-leaf lettuce, halved; 4 slices tomato; 4 thin slices red onion