To save time, you can grill the pork and onions up to a day ahead; refrigerate in separate covered containers. You can also substitute any leftover pork roast.
- 1 large garlic clove
- Coarse salt and ground pepper
- 1 tablespoon vegetable oil, plus more for grates
- 1 pork tenderloin (3/4 to 1 pound)
- 1 large red onion, cut into 1/2-inch-thick slices
- 4 flour tortillas (10-inch or burrito-size)
- 4 tablespoons spicy brown mustard, plus more for serving
- 6 ounces thinly sliced baked ham
- 3 to 4 dill pickles, thinly sliced lengthwise
- 8 ounces provolone or Swiss cheese, coarsely shredded (about 2 cups)
Use garlic and salt to make a paste. In a small bowl, combine with 1/4 teaspoon pepper and the oil. Rub all over pork.
Heat grill to high; oil grates. Place pork on hottest part of grill; cover. Cook, turning occasionally, until an instant-read thermometer inserted in thickest part registers 155 degrees. 10 to 20 minutes. Let rest 5 minutes; thinly slice across the grain.
Meanwhile, place onion slices on cooler part of grill; cover. Cook, turning once, until soft and beginning to brown, about 10 minutes. Reduce grill to medium-low.
Spread 1 tablespoon mustard on each tortilla, leaving a 1/2-inch border. Dividing evenly, layer half of each tortilla with ham, pork, onion, pickles, and cheese. Fold tortillas; press to close.
Lightly oil grates. Place quesadillas on grill; cover. Cook, turning once, until browned in spots and cheese has melted, about 4 minutes. Cut into wedges; serve immediately.