PREPARATION:
- Heat 1/4 teaspoon oil in medium saucepan over medium heat. Add shallots; cook 6 to 8 minutes, stirring occasionally, until golden brown and soft. Set aside.
- Preheat broiler.
- Drizzle each mushroom on both sides with 1/4 teaspoon oil; season both sides with salt and pepper, if desired. Place mushrooms gill-side-up on foil-lined baking sheet. Sprinkle garlic evenly among mushrooms.
- Broil mushrooms 4 minutes per side. Remove from oven.
- Combine mayonnaise and basil until well mixed.
- To assemble burgers, spread both sides of each bun with basil mayonnaise. Divide cooked shallots and mozzarella slices evenly among bottom halves of buns; top with mushroom and bell pepper strips. Replace top halves of buns.
