Process onion and water in a food processor until slushy.

Strain the onion slush through a fine-mesh strainer into a bowl, discarding the solids.

Whisk together ketchup, apple cider, apple cider vinegar, Worcestershire sauce, molasses, Dijon mustard, chipotle chili, adobo sauce, and black pepper with the onion liquid.

In a saucepan, cook bacon over medium-high heat until crisp.

Remove bacon and set aside.

Add garlic and chili powder to the bacon fat and cook until fragrant.

Add the onion-ketchup mixture to the saucepan and simmer for 15 minutes.

Remove from heat and stir in the remaining apple cider vinegar.

(Optional) Pulse cooked bacon in a food processor until finely ground and add to the sauce.