1. Finely dice the onion and crush the garlic, then fry until the onion is soft.
2. Add the wine and bubble until the alcohol has evaporated (the smell will become less pungent).
3. Take off the heat and stir in the sour cream.
4. Return to the heat, let the sauce bubble and add the fish. Turn the heat down to a gentle simmer, cover and cook for 5-10 minutes, depending on the thickness of your fish pieces, until the fish is just cooked.
5. Chop the parsley and add the majority to the pan, saving a small amount to sprinkle over the final plate.
6. Serve with warm, crusty, white buttered bread.