Chipotle Barbecue Sauce

1 tablespoon extra-virgin olive oil
2 cups sliced onions
1 1/2 cups cider vinegar
2 ancho chiles and 6 chipotle chiles,
    stemmed, seeded and roasted
10 large cloves garlic, roasted
1 cup molasses, or to taste
2 1/2 cups catsup
1/2 cup water
Salt, to taste

In a large skillet over medium-high heat, heat the olive oil and saut onions until they are browned and completely soft, about 3 minutes.

Add vinegar and bring it to a simmer. Add chiles to the pan along with the garlic, molasses and catsup; stir well to blend. Simmer for 5 to 8 minutes or until the flavors are blended.

Add some or all of the water to adjust the consistency. Put sauce into a blender and puree it until smooth. Strain sauce through a coarse-meshed sieve.

Store in an airtight container in the refrigerator for up to 8 days.