COOKING INSTRUCTIONS: In a large skillet, heat 1/2 tablespoon of oil over medium-high heat; add onion and mushrooms and cook, stirring often, until softened.
Add zucchini, bell pepper and 1 cup of salsa; cook until vegetables are tender-crisp then transfer to a plate, season with salt and pepper and let cool.
In a large bowl, toss together lettuce and tomatoes with remaining salsa and olive oil; arrange mixture on dinner plates, top with mushroom mixture and sprinkle with cheese.