1 boneless pork shoulder or butt roast, 2 1/2 to 3 lb.
Salt and freshly ground pepper, to taste
1 bottle Frontera Grilled Pineapple & Chipotle   Grilling Sauce
1 ripe pineapple, peeled, cored and cut   crosswise into 1/2-inch-thick slices
Vegetable or olive oil for grilling
Corn or flour tortillas, warmed just before serving