For the basting sauce, in a small saucepan, stir together all ingredients, except the pork. Bring to boiling; remove from heat.
In a covered grill, arrange medium-hot coals around a drip pan. Test for medium heat above the pan. Place tenderloin on the grill rack over drip pan, but not over coals.
Insert a meat thermometer. Baste meat with sauce. Lower the grill hood.
Grill the meat for about 30 to 45 minutes or until thermometer registers 160 degree F, brushing frequently with sauce during the first half of cooking. Store the remaining basting sauce in the refrigerator. Bring the sauce to boiling before using it again. Makes 4 to 6 servings.