Rather than keeping the pork in a marinade, keep it in a brine. The brine is simply a saline solution (salt water), and can have ingredients such as onion and garlic, along with dried herbs and spices.
A marinade usually contains an acidic ingredient, such as wine, vinegar, citric acid, etc. The acid reacts with the outer tissue of the meat, tightening it into a dense structure that inhibits the penetration of the solution into all but the very outer layer of meat. Two to three hours in a marinade is all you need to get the flavor from that marinade. Further marinading is a waste of time.
But a brine will completely saturate the meat tissue, distributing its flavor componants throughout the meat. The salt will act as a preservative and prevent microbial growth if mixed in sufficient quantity. Also, you can add flavorings such as soy, or liquid smoke to a brine if you want.
But even with a brine, you need to be careful. The flavors must be ballanced to avoid creating an overly salty product. I can't give you the proper proportion of salt to water off the top of my head, but there are a number of people here who can.
Flavors that will work with your list of ingredients include most hot peppers, fresh or dried, onion, sage, thyme, rosemary, brown sugar, honey, mustard powder, garlic, and several others. Just remember that pork has a fairly delicate flavor, and can easily be overwhelmed if over spiced. Also, and this is of ultimate importance, do not overcook the meat. Use a meat thermometer and remove the pork from the heat source, be it grill, oven, broiler, or frying pan, when the internal temp reaches 145 degrees F. You can bring it up to 150 if you want, but much more than that and the meat will begin to dry out and toughen. Also, pork reacts favorably to a quick sear, with a bit of salt, to brown the outside of the meat. This adds wonderful flavor.
Hope that helps.
Seeeeeya; Goodweed of the North
