Pre-cook the mushrooms, peppers, and onion by placing them on separate paper towel lined plates, and microwave each for 2 minutes to soften and release excess moisture.
Lightly spray a baking sheet with cooking oil. Spread one side of each bread slice with sour cream. Place the bread, sour cream side up on the baking sheet. Sprinkle all the slices generously with dried dill.
Top each bread slice with mushrooms, peppers, onion and black olive slices. Lightly season with salt and pepper. Add the sliced tomatoes and sliced cheese.
Place into the oven for 10 to 15 minutes until the cheese is melted. Serve right away.