Preheat grill. Brush mushrooms with some of the oil and season with salt and pepper to taste. Grill for 3 to 4 minutes per side, remove and slice into 1/4-inch slices. Place the warm beans in a large bowl, add mushrooms, herbs and tomatoes.
Whisk together the lemon juice, olive oil and garlic and pour over the beans. Add the cheese and season with salt and pepper to taste.