Preheat the oven to 425F. Place the fillets in an oven pan. Bake them for 5 minutes until they lose their water. Dry them and put aside. Heat the oil in a heavy casserole, add the onions, the garlic, tomatoes, white wine, salt, pepper and a pinch Cayenne. Cook over a moderate heat for 15 minutes uncovered. Once the sauce is reduced and thickened, lower the heat and place the pollock fillets in the sauce to simmer for 10 minutes uncovered. Serve the steamed potatoes.