Stem and seed the ancho chiles. Cover with ½ cup warm water or stock and soak 15 to 20 minutes until softened. Purée chiles and liquid into a smooth paste.
Heat the oil in a saucepan over medium. Cook the onion 4 to 5 minutes until translucent. Add garlic and cook 1 minute more.
Stir in tomato paste and cook 2 to 3 minutes until darkened and fragrant.
Add cider vinegar, brown sugar, Worcestershire, and molasses. Stir in the ancho paste and bring to a simmer.
Add cayenne, paprika, ancho chili powder, cumin, salt, and pepper. Simmer on low 20 to 30 minutes, until thick enough to coat a spoon.
Thin with soaking liquid if needed. Taste and adjust salt, sugar, and heat.
Cool to room temperature before serving. For smooth restaurant texture, blend again and strain.