In a frying pan put 3 tablespoons butter and cook until melted and starts to bubble. Add the pieces of fish and gently brown on both sides.
Add to the pan the sweet vermouth, garlic, the capers and salt and pepper. Scrape any bits of the pan and cook until the sauce start to bind.
Remove the fish from the pan when done and rest covered on a dish.
Add the remaining 1 tablespoon butter to the skillet and swirl it around until it melts.
Serve over the fish.