1¼ oz. dried chipotle chiles (about 7), stemmed
3 tbsp. canola oil
1 small white onion, minced
¼ cups agave syrup
¼ cups apple cider vinegar
2 tsp. kosher salt
1 clove garlic, smashed
Heat a 10″ skillet over medium heat; add chiles and toast, turning occasionally, until blistered and blackened, about 8 minutes. Transfer to a blender and set aside. Return skillet to heat and add 2 tbsp. oil; add onion and cook, stirring, until soft and lightly caramelized, about 12 minutes. Transfer to blender, along with syrup, vinegar, salt, garlic, and ¾ cup water; puree until smooth, about 2 minutes.
Heat remaining oil in skillet over medium-low heat, and then add pureed salsa; cook, stirring often, until salsa thickens and turns brick-red in color, about 45 minutes. Let cool.