Chipotle Sauce - white onion

Method

• Line heavy large skillet with foil; heat over medium heat.
• Place onion and garlic in skillet; cook until onion softens and blackens in spots, turning often with tongs, about 15 minutes.
• Transfer onion and garlic to medium bowl.
• Peel garlic.
• Place same foil-lined skillet over medium-high heat.
• Working in 2 batches, cook tomatoes in skillet until tender and skins blister and blacken, turning occasionally, about 20 minutes.
• Transfer to large bowl; cool and peel.
• Working in batches, puree tomatoes, onion, garlic, and chiles in blender until smooth.
• Heat oil in heavy large deep skillet over medium-high heat.
• Carefully add tomato puree to skillet (mixture will bubble vigorously).
• Stir in salt.
• Reduce heat; simmer gently until sauce thickens slightly, stirring often, about 15 minutes.