1/2 cup balsamic vinegar
4 tablespoons of maple syrup
5 medium red apples cored and cut into wedges
2 large red or sweet onions cut into 1/2 inch chunks
2 tablespoons of extra virgin olive oil
Freshly ground salt & pepper
2 pork tenderloins about 10-12oz each trimmed of excessive fat
Place one oven rack in top third of oven, and another rack in bottom third. Preheat oven to 450 degrees. Make glaze: In a small saucepan, bring vinegar and maple syrup to a boil over high heat; cook, stirring occasionally, until mixture has reduced to 1/2 cup, 3 to 4 minutes. Remove from heat; transfer 2 tablespoons to a small bowl for drizzling, and set aside. Reserve the rest of the glaze in saucepan.
On a large rimmed baking sheet, toss apples and onion with oil. Season with salt and pepper; arrange in a single layer, and roast until golden, about 10 minutes. Remove from oven and toss.
Meanwhile, line another rimmed baking sheet with aluminum foil; place pork on foil. Pat dry on both sides with a paper towel. Pour olive oil generously all over the pork. Season generously with salt and pepper; brush with glaze from saucepan. Return apples and onion to oven, on bottom rack. Place pork on top rack; roast 10 minutes. Remove pork from oven; brush with glaze (discard any remaining in pan). Roast until pork registers 150 degrees.on an instant-read thermometer, and apples and onion are tender, about 10 minutes more.
Transfer pork to a cutting board, and let rest 10 minutes. Slice 1/4 inch thick; drizzle with reserved tablespoon glaze. Serve on top with apples & onion.