Step 1

Combine the tomatoes, chiles and garlic in a medium saucepan, cover with water and bring to a boil over medium-high heat. Reduce heat to medium and simmer for 10 to 15 minutes, until tomatoes are completely cooked and mushy and the chiles are plumped and rehydrated.

Step 2

Transfer the tomatoes, chiles and garlic to a blender, add the onion, salt and pepper, and purée until completely smooth.

Step 3

Heat the oil in a medium saucepan over medium heat. Once hot, pour in the tomato sauce, cover partially and simmer for 5 to 6 minutes, stirring occasionally, until the flavors and color have deepened and the sauce has thickened slightly. Serve hot, warm, room temperature or chilled. The salsa will keep for 5 days in the refrigerator.