1Heat gas or charcoal grill. Place onion, bell pepper and garlic in grill basket (grill “wok”). Place basket on grill over medium heat. Cover grill; cook 10 to 15 minutes, stirring vegetables occasionally, until tender.
2In blender, place remaining ingredients. Add grilled vegetables. Cover; blend on high speed until pureed.
3Transfer sauce to jars or resealable containers. Cover; refrigerate 8 hours or overnight to blend flavors.