what to do
1 tablespoon unsalted butter.
1/2 small, sweet onion, diced.
1 garlic clove, minced.
1/2 teaspoon coarse salt
1/4 teaspoon freshly ground black pepper.
1/8 teaspoon crushed red pepper flakes.
1 tablespoon tomato paste.
1 tablespoon apple cider vinegar.
1/3 cup packed dark brown sugar.
1/3 cup Worcestershire sauce.
1 cup ketchup.
1/2 canned chipotle chili pepper in adobo, or more to taste.
what you need
1. In a large saucepan, heat the butter over low heat. Add the onions and garlic, and season with the salt, black pepper, and crushed red pepper flakes. Cook until the onions are translucent, about 3-5 minutes.
2. Add the tomato paste, whisk to combine, and cook for 1 minute. Add the vinegar and scrape any browned bits from the bottom of the pan. Add the brown sugar, Worcestershire, ketchup, and the chipotle. Stir well to combine and reduce the heat to low.
3. Using an immersion blender (or transferring the sauce to a countertop blender), pulse until smooth. Simmer on low, stirring occasionally, for at least 30 minutes or preferably for 1 hour, which will make the flavours even richer. Season to taste with additional salt if necessary.
4. Cool slightly and refrigerate until ready to use.
You can store the sauce in an airtight container in the fridge for 7-10 days.