For the marinade, combine fruit juices, water, garlic, oregano, cumin, salt, and the bay leaves in a large shallow baking dish. Pierce boneless pork roast in several places with a large fork. lace in dish and turn to coat. Chill, covered in the refrigerator for 6 to 24 hours, turning occasionally.

Remove meat from te marinade; reserve marinade. Brown meat on all sides in hot cooking oil in a large skillet. Place onions in a 3 1/2,-, 4-, 5- or 6-quart crockery cooker. Place meat on top of the onions. Sprinkle with salt and pepper. Add reserved marinade. Cover, cook on the low heat setting for 10-12 hours or the high heat setting for 4 1/2 to 5 hours.

To serve, shred and serve on buns, if desired. Or, slice and serve with cooking juices.