Traditional Italian Tomato Sauce

Rinse the tomatoes and score on the bottom. Blanch in boiling water until the skin begins to burst. Remove from the water and place in an ice water bath. Drain thoroughly and peel. Cut the tomatoes into quarters, remove the seeds and core, and finely dice. Pass the pieces of the core through a fine strainer, reserving the juice. Peel and finely dice the onion and garlic. 

Heat the oil in a pot, and sauté the onions and garlic until translucent. Add the tomato paste, sauté briefly, then add the tomato juice and the diced tomato. Bring to a boil, stirring occasionally. Reduce the heat and simmer for 15 minutes. Add some water, if necessary. 

Puree if you'd like, or leave as it is.