Slice onion and limes in half.
In a dry heavy bottom skillet char the onions and limes (flesh side down) for 5 - 10 minutes or until charred but not burnt.
Chop charred onion into chunks and add to blender with the roasted tomatoes, juice from the limes, apple cider vinegar, garlic, chipotles and adobo sauce, salt and pepper. Blend on low to medium speed until broken down into a thick sauce consistency (about 30 seconds).
Taste and adjust spice and salt levels as desired.
Add corn and blend on medium for 10 - 15 seconds. Allow some of the corn to break down but leave some chunky bits.
Store covered in the refrigerator for up to 5 days.
Serving: 4oz | Calories: 14kcal | Carbohydrates: 3g | Protein: 1g | Fat: 1g | Saturated Fat: 1g | Sodium: 365mg | Potassium: 21mg | Fiber: 1g | Sugar: 1g | Vitamin A: 142IU | Vitamin C: 3mg | Calcium: 10mg | Iron: 1mg