Dissolve the salt and brown sugar in 1/4 cup warm water. Pour into a heavy duty gallon size ziplock bag safe for food storage. Add the remaining water to the bag. Stir. Add the pork loins. Seal the bag. Refigerate overnight. Rinse pork before putting in marinade. Throw brine and plastic bag away.
Combine marinade ingredients in small bowl. Microwave for 30 seconds to 1 minute to melt peanut butter. Stir well. Reserve 1/2 to 3/4 cup. Cover and refrigerate reserved marinade. This sauce will be served with the cooked pork.
Pour remaining marinade in new ziplock bag. Add pork. Squeeze all air out of bag. Refrigerate overnight.
Fire up the barbecue to a medium temperature.
Take pork out of marinade. Let sit at room temp for about 20 minutes. Pour marinade in small saucepan. Heat to a boil; boil for 3 minutes. If marinade gets too thick, add a little milk to thin.
Take the reserved 1/2 cup or 3/4 cup sauce out of refrigerator to warm to room temp.
Grill pork loins until internal temp reaches 155 degrees. When pork reaches 125 or so, baste with the boiled marinade. Watch pork carefully after basting so that it doesn't burn. Use a BBq spatula to roll the pork around. Pork will take about 15 minutes to cook.
Pull off the grill and let sit for 5 minutes before slicing into thin slices.
Dress each plate with a dollop of the room temp sauce. Place pork slices on top of sauce.
Wonderful served with udon noodles dressed with sesame oil and soy sauce.