Over medium heat, add a little butter or oil to a pan and sauté Onion until tender and starts to get translucent, about 7-8 minutes. While onion is cooking, you can measure out all the spices you'll be adding in step 3!
Add in Garlic, and cook another couple of minutes. Stir often to keep the small pieces of garlic from burning.
Add Ancho Chili Powder, Garlic Powder, Cinnamon, and Nutmeg, and cook for 1 more minute.
Take a second to appreciate the aroma of the spices hitting the hot pan and think about how good life is. Keep stirring every few seconds.
Add Tomato Paste, cook one more minute.
Add in Diced Tomatoes, Brown Sugar, Apple Cider Vinegar, and Worcestershire. Turn heat down to medium-low and let simmer for about 20 minutes.
Take off the heat and give it some time to cool. Purée until smooth (if you want to leave some chunks that's fine too) in a blender or food processor. If you do this while the mixture is still hot, the steam may burn you!
Taste and add salt and pepper if necessary. Great warm, fine cold too.