Enchilada Sauce

From Everyday Food.

3 Tbsp. extra-virgin olive oil
3 garlic cloves, roughly chopped
1 large white onion, diced small (1/2 C. reserved for serving)
4 tsp. chili powder
2 Tbsp. white vinegar
1 can (15 oz.) tomato puree
2 C. low-sodium vegetable broth

In a medium saucepan, heat oil over medium-high. Add garlic and onion and cook, stirring occasionally, until onion softens, 5 minutes. Add chili powder and cook until fragrant, 1 minute. Whisk in vinegar, tomato puree, and broth; bring to a simmer and cook 5 minutes. Season with salt and pepper. Transfer mixture to a blender and puree until smooth (use caution when blending hot liquids).

Refrigerate extra sauce in an airtight container, up to 1 week, or freeze, up to 3 months.