1) Turn the broiler to high and cover a baking sheet with foil, or use a silicon baking liner. Place fish on the pan.
2) Spread a thin layer of miso paste (mixed with water and/or lemon juice) over the fish fillets. Spritz on or pour half the olive oil over the fillets and then season them with salt and pepper.
3) Peel several ribbons from one side until you reach the seeds, then turn the zucchini and peel away more ribbons until all that's left is the core. Thinly slice or spiral the bell peppers and red onions to add color and flavor (optional). Toss all vegetables in a bowl with the remaining olive oil and salt and pepper. Arrange the vegetables around the fish on the baking sheet.
4) Place the pan of fish and vegetables under the broiler on the top rack of your oven, about four inches below the heating element. Cook the fish for two to four minutes, or until the fish is opaque, and a knife slides easily into the thickest part of the fillets. Make sure you don’t overcook them!
5) Transfer the cooked fish to a plate and continue to broil the vegetables if they need more time, until tender and browned on the edges. Serve fish and vegetables alone or with a whole grain like quinoa, farrow, sorghum, or brown rice.