Before marinating, score the fat to allow the flavors to better infuse the meat, and let the loin soak from two to 24 hours, turning two or three times. Chinese five-spice powder is a blend of spices that usually combines cinnamon, star anise, nutmeg, all-spice, and Szechuan peppercorns in equal measure. It imparts a distinctive, pungent flavor and can be found in Asian specialty stores and some supermarkets.
1/2 cup fresh orange juice
2 tablespoons frozen orange-juice concentrate
2 tablespoons honey
1 tablespoon soy sauce
1 tablespoon olive oil
1 teaspoon minced garlic
1 teaspoon minced fresh ginger
1/2 teaspoon Chinese five-spice powder
1 teaspoon Asian chile paste
2 to 3 drops hot chile oil
1 boneless pork-loin roast (4 to 4 1/2 pounds), trimmed
Vegetable-oil cooking spray
Combine orange juice, juice concentrate, honey, soy sauce, olive oil, garlic, ginger, five-spice powder, chile paste, and chile oil in a bowl, stirring well.
Put the roast in a shallow glass or ceramic dish, and pour the marinade over it. Turn to coat. Cover, and refrigerate for at least 2 hours and as long as 24 hours.
Prepare a charcoal or gas grill, arranging the coals for indirect cooking. Lightly spray the grill rack with vegetable-oil cooking spray. The coals should be moderately hot.
Lift the roast from the marinade, reserving the marinade and brushing it on the roast 2 or 3 times during the first 30 minutes of cooking. Grill over indirect heat with the grill covered for about 1 hour 10 minutes, or until a meat thermometer inserted in the center of the roast registers 150 degrees to 155 degrees. Remove the roast from the grill, and let it rest for about 10 minutes before slicing.