Pan-fried mackerel with tangy sauce

Mackerel is a fish that's not much eaten in Australia, unlike in Europe, but that's a pity, because it's a delicious fish with a firm juicy white texture and a distinctive taste. And it's very
reasonably priced too!

We had lovely cutlets of it the other day, pan-fried with a simple, tangy sauce. First, you pan-fry the mackerel till done, salt and pepper, then set aside, add chopped onion, garlic and parsley to the cooking juices, cook half a minute, then add red wine vinegar, cook till a little reduced, add a small lump of butter, stir, then pour over the fish and serve!
Perfect with small boiled potatoes and chopped spinach.