Core and dice the tomatoes on a trenched cutting board. Save the cut tomatoes and the juice in a large bowl.
Coat the bottom of the Dutch oven or large pot with olive oil and saute the chopped onion over a medium low heat until they have turned soft and translucent. (about 10 minutes)
Add the minced garlic.
Add the tomatoes, a few additional touches of olive oil and simmer for ½ to 3 hours.