Slice the onion finely and peel the garlic.  Saute in olive oil over a medium heat until the onion becomes translucent.

Chop the cherry tomatoes in half, or peel and chop the larger tomatoes.  Add them to the onions. Add the bay leaf and let the mixture simmer for 10 minutes, stirring occasionally.

Add the fish fillets, skin side down, or whole fish, and the wine salt and pepper.  Let simmer on a medium low heat until the fish is cooked through (this won't take long: about 5 minutes).  If using whole fish, the cooking time will be a bit longer.  You should turn them over halfway through the cooking time.  If the mixture starts to dry out, add a little more wine.

Chop the parsley and sprinkle it over the top when the fish is ready.