In a saucepan or saucepan with a thick bottom, heat the oil, add the finely chopped onion and cook for 8-10 minutes until it becomes transparent. When the onion softens, add the mashed tomatoes, crushed garlic and spices, season with salt and pepper to taste. To interfere. Cover loosely and cook over low heat for at least 30 minutes, stirring occasionally and adding the drained tomato juice if the sauce thickens too much. This sauce can be prepared in advance and stored in the refrigerator or frozen.