Put the water to boil and parboil the tomatoes for about a minute. Then take them out, put them under cold running water to cool and peel them. Put the tomatoes in a blender, along with the tomato paste, parsley, garlic, oregano, salt and pepper.
Whisk until you get a puree. Sauté the onion with the olive oil in a frying pan or pot for a few minutes. Add the tomato sauce and white wine. Simmer the sauce for 30 minutes, while stirring.