For apples: in large skillet or pan, melt butter over medium heat; add apples. Cook, stirring constantly til apples are almost tender about 6 to 7 minutes. Disso0lve cornstarch in water, add to skillet. Stir in brown sugar and cinnamon. Boil for 2 minutes, stirring occasionally. Remove from heat and serve warm.
For pork: Preheat oven to 400. Mix 2 tsp. salt,1 tsp. pepper, and 1/4 tsp. cinnamon. Sprinkle on both sides of medallions.
Sear medallions in oil in saute pan over high heat til brownd, 5 minutes. Flip medallions, transfer pan to oven, and roast til an instant read thermometer inserted into the thickest part registers 140, 10 to 12 minutes. Transfer medallions to a plate, tent with foil and allow-them to reach an internals temperature of 145. Serve with sauteed apples
Note: I didn't use pork tenderloins for this dish, but I did have thick boneless pork chops. I sauteed them, cutting the amount of salt, pepper and cinnamon in half, as there were only two thick pork chops. Everything else stayed the same.