How to Make It
Preheat broiler to high. Place jalapenos and onion slice on a baking sheet; coat with cooking spray. Broil 5 minutes; turn vegetables. Add garlic cloves; broil 5 minutes. Wrap mixture tightly in foil. Let stand 20 minutes. Peel and seed peppers.
Place peppers, onion, garlic, lime juice, water, sugar, and salt in a blender; process until smooth.
Store in refrigerator in an airtight container for 7 to 10 days. If sauce separates, give it a good stir or shake.