Step 1

Place 2 pork tenderloins (about 2 lb. total) on a small rimmed baking sheet and season all over with kosher salt and freshly ground black pepper.

Step 2

Combine ¼ cup honey, ½ tsp. crushed red pepper flakes, and 1 cup red wine vinegar in a measuring glass or small bowl and stir to dissolve honey; set aside.

Step 3

Heat 2 Tbsp. extra-virgin olive oil in a large skillet over medium-high. Cook tenderloins, turning occasionally, until golden brown all over, 6–8 minutes total. Using tongs, transfer to a large plate.

Step 4

Add remaining 1 Tbsp. extra-virgin olive oil to pan and arrange 12 oz. shallots (about 11 medium), peeled, halved lengthwise, or 2 small red onions, quartered, cut side down, in skillet; season with salt. Cook, undisturbed, until beginning to char underneath, about 3 minutes. Scoot shallots to edges of skillet and return tenderloins along with any juices that have collected on plate to pan. Add reserved vinegar mixture and bring to a simmer. Cook, turning pork every few minutes and reducing heat as necessary to maintain a gentle simmer, until an instant-read thermometer inserted into thickest part of meat registers 140° and shallots are tender, 7–12 minutes. Transfer tenderloins to a cutting board and let rest 10 minutes.

Step 5

While pork is resting, add 2 cups pitted fresh (or frozen) sweet cherries (about 10 oz.) to pan and cook, stirring, until cherries are warmed through and sauce is beginning to look syrupy, about 4 minutes (you may need a couple minutes more if using frozen cherries). Remove from heat. Add 3 Tbsp. unsalted butter, cut into pieces, and remaining 2 Tbsp. red wine vinegar and swirl to combine; season with salt.

Step 6

Slice pork and arrange on a platter or plates. Spoon agrodolce cherries and shallots over.