Place fish in Pyrex dish and season both sides of fish with salt, pepper and oregano. Set aside.
In a sauté pan set on medium heat, add olive oil, onion and garlic. Sauté about 7 - 8 minutes or until onions and garlic become slightly caramelized. Add wine and allow to cook 5 - 7 minutes or until almost completely evaporated.
Add in sauce along with capers and olives and bring to a simmer. Remove from heat and pour hot sauce evenly over raw seasoned fish.
Bake in oven 10 - 12 minutes or until internal temperature of the fish is 140ºF. Serve while hot and season to taste with more salt and pepper as needed. This dish goes great with polenta or wild rice.