Spaghetti with Tomato Sauce

Rinse the tomatoes and blanch in boiling water. Halve the tomatoes, remove the peel and seeds, and finely dice. Peel and finely dice the onion. Heat the olive oil in a saucepan and sauté until golden brown. Add the tomatoes and continue to cook, stirring constantly. Mix in 1 teaspoon of sugar, cover, and simmer for 5-8 minutes. Mix in the butter, then season to taste with salt and pepper.