Remove the stems, seeds, and veins off the ancho chiles, chipotle peppers, and jalapeño peppers.
Place the ancho chiles in a pot filled with water and boil the chiles for about 15 minutes over medium heat.
Remove the ancho chiles out of the water and drain them.
Place the softened ancho chiles, chipotle peppers, adobo sauce, jalapeño, cilantro, garlic, orange juice, lime juice, and vinegar into a processor and blend.
Season the Flank steak on both sides with kosher salt
Place the seasoned flank steak in a plastic bag along with the chiles mixture.
Place in the fridge for a minimum of 2 hours, preferably over night.
Cook the flank steak over high heat for about 7-8 minutes on each side for medium rare
While the flank steak cooks, grill or deep fry some corn tortillas.
Chop the flank steak into bite sized pieces, check for seasoning, it's not too late to add more salt if needed.
Serve tacos with guacamole, raw onions, cilantro, and hot sauce!