1. Preheat oven to 375◦ F
2. Season the salmon fillet with salt and pepper. Brush an even thick coating of the mustard all over the salmon.
3. Place the salmon on a parchment or foil lined baking sheet. Place the fish horizontally in front of you. Starting at the left end of the fillet, lay a column of overlapping slice of the zucchini. On the next row lay a column of overlapping slices of the squash, they should be overlapping the zucchini a bit as well. On the next row, lay a column of overlapping slices o tomatoes, they should slightly overlap on the squash. Begin again with the zucchini, followed by the squash and the tomato. Continue in this fashion until the whole fillet is covered.
4. In a small bowl, mix the breadcrumbs, dill, and olive oil. Sprinkle over the top of the vegetables.
5. Bake for 30-35 minutes. Remove one of the vegetables in the thickest part of the fillet and test to make sure the fish is done, and then cover it back up with the vegetable.
6. Serve hot or at room temperature. Can be refrigerated overnight and brought to room temperature the next day.