4 red or black Champlain Orchards plums (such as Methley, Bluebyrd, or President)
1 tablespoon olive oil
1 large shallot, sliced lengthwise
1/2 cup (packed) light brown sugar
1/4 cup Sherry vinegar or apple cider vinegar
1 tablespoon chopped garlic
1 tablespoon mustard seeds
2 teaspoons grated peeled ginger
1/2 teaspoon freshly ground black pepper
1 bay leaf
2 tablespoons minced fresh rosemary
4 teaspoons herbes de Provence
4 teaspoons olive oil
2 pork tenderloins (about 2 lb.)
Kosher salt and freshly ground black pepper
16 thin slices pancetta (Italian bacon; about 8 oz.) or prosciutto
Peel plums, if desired Halve and pit. Cut into 1/2" wedges.
Heat oil in a medium saucepan over medium heat. Add shallot and cook, stirring occasionally, until shallot begins to soften, about 2 minutes. Add brown sugar, next 6 ingredients, and 1/4 cup water. Cook, stirring occasionally, until mixture is fragrant, about 2 minutes. Stir in plums. Cover and simmer over medium heat, stirring occasionally, for 8 minutes. Uncover and continue cooking, stirring occasionally, until fruit is soft and juices have thickened, 20–25 minutes. Season to taste with salt. Let cool slightly. DO AHEAD: Chutney can be made 1 week ahead. Cover and chill. Rewarm slightly before serving.
Stir rosemary, herbes de Provence, and oil in a small bowl. Rub all over pork; season with salt and pepper. Wrap pancetta slices around pork and tie at 2" intervals with kitchen twine to hold together. DO AHEAD: Can be made 1 day ahead. Cover and chill.
If using a charcoal grill, build a medium-hot fire; push coals over to 1 side of grill. If using a gas grill, heat all but 1 burner to high. Grill tenderloins over hot part of grill, turning frequently, until a crisp brown crust forms on all sides, 8—10 minutes. Move tenderloins to cooler part of grill to gently cook through; cover and cook until an instant-read thermometer inserted into the middle of each loin registers 145°, 15—20 minutes longer.
Transfer tenderloins to a cutting board. Let rest for 10 minutes. Slice thinly and serve with plum chutney alongside.
TEST KITCHEN TIP: How to Peel Stone Fruit
Bring a medium saucepan of water to a boil. Using the tip of a paring knife, make 2 shallow 1" cuts to form an X on the bottom of the fruit.
Add fruit to water and cook just until skin begins to peel back at each X, 30–60 seconds.
Using a slotted spoon, transfer fruit to a medium bowl of ice water; let cool. Using a paring knife and your fingers, peel fruit.
If you don't care about smooth surfaces for presentation purposes, a serrated peeler's sharp-toothed edges quickly and easily peel soft fruit.
Adapted from Bon Appetite/Susan Spungen