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Ingredients
- 3 C finely diced Spanish onions (about 1 pound)
- 1 C extra virgin olive oil
- to taste, kosher salt
- 1 pound plum tomatoes (about 6)
- 1/2 tsp garlic, minced
Preparation
Step 1
Combine the onions, oil, and a pinch of salt in a 8-9″ wide saucepan and place over medium heat. Bring the oil to a simmer and reduce the heat to low. (If you have a diffuser like a Flame-tamer, place this underneath the pan). The oil should only bubble gently, slowly cooking and caramelizing the onions. Stir as needed to maintain even cooking, scraping any stray bits of onion that may stick to the sides of the pan. The oil will become cloudy, but then clear as moisture evaporates. Cook about 2 1/2 hours, or until the onions are a rich, golden brown (a “shade darker than a golden raisin”) and the oil is clarified.
Meanwhile, cut the tomatoes lengthwise in half. Gently squeeze out the seeds. Discard seeds. Hold the cut side of each half against the large holes of a box grater and grate. Discard the skins. This should yield about 1 cup of tomato purée.
Add the tomatoes to the onions and cook for about 2 to 2 1/2 hours more, or until the onions and tomatoes begin to fry in the oil. The mixture should sizzle, with small bubbles covering the entire surface. Gently stir, separating the onions and tomato from the oil and turn off the heat. Add another pinch of salt and the garlic. Stir to incorporate, and allow to cool in the pan.