In a large resealable bag, combine the first 9 ingredients to create the marinade.
Add the pork loin and marinate for about 4 hours turning several times.
Preheat the oven to 350 degrees.
Place a large skillet coated with cooking spray over medium high heat.
Remove the loin from the marinade and pat it semi-dry. Reserve the marinade mixture.
Sear the loin on all sides, including the ends, in the hot skillet. Set the skillet aside without cleaning it (leave all the juices and cooked bits in it) and keep it for later as well.
Place the seared loin on a rack in a shallow pan. Add the 1 cup of chicken broth to the pan.
Cook for 40-50 minutes or until the internal temperature is 145 degrees (about 20-25 minutes per pound). Remove from the oven and let rest for 5 minutes before slicing.
During the last 15 minutes of cooking time, transfer the reserved marinade to a small pan and bring it to a rolling boil. Lower the heat but keep the marinade at a slow boil for ten minutes.
Put the skillet that you seared the loin in back over medium-high heat.
Pass the boiled marinade through a strainer into the skillet. Add the remaining ½ cup of chicken broth. Cook, stirring to loosen any cooked bits from the bottom of the pan. Bring to a low boil.
Add the butter and stir until melted.
Slice the loin in about ½” thick slices. Drizzle with the pan sauce.
Pork loin is usually available in about 4-pound pieces. I often purchase one of those and cut it in half. One part is then cut into six nice center-cut chops and the other half becomes a 2-pound roast which will easily serve four people. If you want to cook the full 4-pound loin, simply double the marinade ingredients.
I recommend Colman's brand of dry mustard. If you don't have dry mustard, two teaspoons of Dijon mustard is a good substitute.
No need to use expensive extra virgin olive oil; plain old olive oil is fine.
If you're watching your salt intake you may want to use a lower-sodium brand of soy sauce.
You can use this recipe for pork chops, pork tenderloin, or chicken. Smaller cuts will cook much faster than a loin so be sure to check with a thermometer.
Add some heat to the marinade with a dash of cayenne pepper, red pepper flakes, or your favorite hot sauce.
Try deglazing the pan with white wine instead of chicken broth. Wine really enhances the natural flavors of the pork.
Use an instant-read thermometer to check doneness for best results.
A marinade that has been in contact with raw meat should be brought to a strong boil with the boil maintained for 10 minutes before using in a finished sauce. Do not skip that step!To grill, sear the marinated pork loin over high heat and then continue to grill over medium, indirect heat with the grill covered for 45 minutes to 1 hour. Tent the loin and let it rest for at least 10 minutes.