1. In a large bowl, mix ground pork, chorizo, bacon, olive oil, shallots, parsley, thyme, and cumin. Form mixture into four equal patties about 3/4 inch thick.
2. Lay burgers on a barbecue grill over a bed of medium-hot coals or medium-high heat on a gas grill (you can hold your hand at grill level only 3 to 4 seconds); close lid on gas grill. Cook burgers, turning once, just until no longer pink in the middle (except for pieces of chorizo; cut to test), 13 to 15 minutes total; keep a spray bottle of water handy to douse any flames. Set burgers on buns.