Sofrito – from DahliaLady

Sofrito [soh-FREE-toh] is a Spanish/Italian sauce made from sautéed garlic, onion and bell pepper. (Other ingredients are optional.) The veggies are sautéed over very low heat until very soft. The mix can then be added to other dishes. For example, omelets filled with a bit of sofrito and diced ham are wonderful.

The following information is taken from epicurious.com:
 

1. The Spanish sofrito  is a sauce made by sautéing annatto seeds in rendered pork fat. (Note: These are mostly for colour. You don't need them. A pinch of saffron, or a dash of turmeric for the wallet-ly challenged, will give a similar effect.) The seeds are removed before chopped onions, green peppers, garlic, pork and various herbs are cooked in the flavoured, now-red oil until the ingredients are tender and the mixture is thick. The sauce is used in recipes as needed.
2. The Italian soffrito is a similar mixture (usually chopped celery, green peppers, onions, garlic and herbs) sautéed in olive oil and used to flavour soups, sauces and meat dishes. "

These directions are taken from a recipe on the same site:

1 tablespoon minced onion
1 tablespoon minced red or green bell pepper
1 tablespoon chopped fresh coriander sprigs

[Note: Coriander sprigs are also sold as cilantro. I chose this version because the coriander/cilantro would give it a Mexican feel, which fits the thread. However, the cilantro is not part of a classic sofrito. Also, cilantro is NOT the same thing as Italian parsley, although it looks like it. People either love it or hate it. I love it.]

In a 1 1/2-quart heavy saucepan cook onion, bell pepper, coriander, and garlic in oil over moderately low heat, stirring, until vegetables are soft, about 5 minutes.

[When I cook this, I heat the olive oil in a 12" sauté pan over a medium fire. When it's thoroughly hot,  I add the onion and bell pepper, and sauté them for a minute or so, to get them thoroughly coated in the oil. Then I reduce the heat as low as possible, cover the pan, and cook them, stirring occasionally, for at least 7 minutes, and preferably 10, until very soft. Now I add the garlic and cilantro, and cook for at least 5 minutes more. The end result should be meltingly soft.)