Portobella Mushroom Burger with Avocados

4 medium portabella mushrooms, stems removed
1 medium onion, cut into 1/2 inch slices
3 tbsp olive oil
3/4 tsp salt, divided
1/2 teaspoon ground black pepper, divided
1 avocado, sliced
2 tbsp low-fat yogurt
1/2 tsp minced garlic
4 hamburger buns, lightly toasted
4 roasted red peppers, from a jar

Brush mushrooms and onion slices with oil; sprinkle with 1/2
teaspoon of the salt and 1/4 teaspoon of the pepper.

Heat large skillet or grill pan over medium heat until hot.

Add mushrooms; cook until tender, 8 to 10 minutes, turning once.

Transfer mushrooms to plate, cavity side up; cover to keep warm.

In same skillet, cook onion slices until golden, about 8
minutes, turning occasionally.

Meanwhile, combine in small bowl, 1/2 of the avocado, yogurt,
garlic and remaining 1/4 teaspoon each salt and pepper; mash
until smooth.

Spoon onions and roasted peppers into mushroom cavities, divided
equally. Spread smooth Avocado mixture on bottom of each bun;
top each with stuffed mushrooms.

Top with remaining sliced avocado. Cover with tops of buns.

Makes 4 vegetarian portabella mushroom burgers.