Chipottle pork ribs

Name: Chipottle pork ribs
Cuisine: American
Ingredients: Spice Marinade; 100g onion, peeled and quartered; 3 cloves garlic; 100g brown sugar; 1 Tbsp Chipotle chilli powder; 1 tsp salt; 2 tsp mustard powder; 1 tsp ground pepper; 150g water; 2-2.5kg pork back ribs; Chipotle Barbecue Sauce; 50g onion; 2 cloves garlic; 30g butter; 1 tsp paprika; 1 tsp Chipotle chilli powder; 180g tomato sauce; 50g brown sugar; 60g apple cider vinegar; 10g Dijon mustard; 20g Worcestershire sauce