In a medium cast-iron casserole, heat 2 tablespoons of olive oil. Add the chicken and cook over high heat, turning once, until nicely browned, about 2 minutes per side. Add the chile powder, cumin and 1 cup of water; season with salt and bring to a simmer. Cover and cook over low heat until the chicken pulls easily with a fork, about 1 hour. Transfer the chicken to a cutting board or bowl and shred, then return to the cooking liquid; stir in the barbecue sauce. Meanwhile, in a medium bowl, whisk the mayonnaise with the vinegar and honey. Add the cabbage, season with salt and toss. On a microwave-safe plate, microwave the tortillas at high power for 30 seconds, until soft and pliable. Serve the chicken with the tortillas, slaw and queso fresco.