2 ancho chiles, stemmed and seeded
2 tablespoons vegetable oil
1 small onion, finely sliced
2 medium cloves garlic, grated on a microplane grater (about 2 teaspoons)
2 teaspoon dried oregano
1 tablespoon cider vinegar
1 chipotle chili and 1 tablespoon sauce from 1 can chipotles en adobo
2/3 cup sour cream or Mexican crema
2 teaspoons fresh juice from 2 limes
Kosher salt and freshly ground black pepper
2 1/2 pounds asparagus (green, white, or a mix), bottoms trimmed, cut into 1-inch segments
24 corn tortillas warmed
Pickled Red Oniona
Queso fresco or queso cotija
Fresh cilantro leaves
Lime wedges