In order to prepare Salmon with Tomatoes, Spinach, and Mushrooms, you will need the following ingredients: 1 chopped tomato, four salmon fillets, cooking spray, fresh spinach leaves, salad dressing, and 1 cup of sliced mushrooms. Preheat oven to 375 degrees. A quick way to slice mushrooms is to use your egg slicer. Spray a baking dish with cooking spray. Rinse spinach well. Place the four salmon fillets skin side down in the dish. In a bowl, combine salad dressing, 1 cup of mushrooms, spinach, and chopped tomato. Mix well. Pour the contents over the salmon. Bake for 20-25 minutes at 375 degrees. Serve.