Prep your fish by patting it dry with a paper towel and place it in a baking dish. Coat the top of the fish with the mustard, top with the lemon slices (I used three per filet) and squeeze the extra juice over the filets. Spread the olives over the fish and place the rosemary on top. Sprinkle with salt and pepper and baked for 10 – 12 minutes, until the fish flakes easily.
While the fish is cooking, simply saute your mushrooms and place them, along with the scallions over a bed of mixed greens.
When the fish is cooked, let it cool for a few minutes, then place it on your salad. Drizzle with balsamic vinegar and a little olive oil and enjoy!