Preheat the oven to 300 degrees. Place rack in lower (not lowest) part of the oven. Spray a large shallow roasting pan with cooking spray (big enough that the entire pork can sit in, but not so wide that there is excessive space between the pork and the walls of the dish).
Score the fat on the top of the pork butt in a crosshatch pattern with a sharp knife, cutting through the fat but not into the meat. Poke a few holes all over the roast with the knife as well, just to allow the sauce to penetrate into the meat better.
Place the garlic, onion, jalapeño, and oregano in a food processor (or blender) and pulse until finely chopped. Add the cumin, chili powder, salt and pepper and process for about 30 seconds to make a paste. Add the vinegar and olive oil and process to incorporate until a thick, spreadable paste is formed.
Place the roast in the roasting pan, and rub the spice mixture all over the roast to fully coat. Pour 2 C of white wine into the bottom of the roasting pan. Spray the underside of tinfoil with cooking spray, and cover the roasting pan tightly with the aluminum foil., tenting the top so it's not touching the top of the roast very much.
Place in the oven and roast for 2 1/2 hours. Remove aluminum foil, and roast uncovered for another 3 1/2 - 4 hours (possibly 4 1/2 hours depending on your oven). If it starts to look dry on the bottom, add a bit more wine or water. It's cooked when you insert a fork and it's very, very tender with little resistance, and the blade bone can easily be pulled out with minimal effort.
Remove from oven and tent loosely with foil. Let rest 15-30 minutes and then slice.
Enjoy!