1 (3 pound) boneless pork loin
1 (12 ounce) can beer
1/2 cup dark corn syrup
1/2 cup finely chopped onion
1/3 cup prepared mustard
1/4 cup vegetable oil
1 to 2 tablespoons chili powder
2 cloves garlic, minced 

Place pork loin in a large shallow glass or enamel dish. In a medium bowl, stir together remaining ingredients; pour over pork. Cover and refrigerate overnight, turning occasionally.

Remove pork from marinade. Place over drip pan on grill. Grill, covered, with banked charcoal or on gas grill. Baste frequently with marinade. Remove from grill when meat thermometer reads 155 degrees F, about 1 to 1 1/2 hours.

Let rest 10 minutes before slicing thinly to serve, allowing internal temperature to rise to 160 degrees F.