Trim the silver skin off the pork tenderloin with a sharp knife. Don't worry about the little pieces of fat - they will melt right off.
Season with salt to taste and then coat it with cracked black pepper. Use tongs to turn and roll the pork tenderloin, patting it all over so that it is completely encrusted in the black pepper. What you want is a nice spicy black pepper crust to counter balance that sweet savory delicious black cherry sauce.
Pre-heat oven to 375F. Heat oil in a skillet and brown the tenderloin on all four sides, about 3-4 minutes per side.
Transfer skillet to the oven and cook for 20 minutes for medium. Take skillet out of the oven and transfer tenderloin to a cutting board, loosely cover with foil and let it rest.
Meanwhile, using the same hot skillet, add the minced garlic, vinegar, chicken stock and black cherry preserve. Stir well and cook until it has reduced by about half. Turn heat off. Then whisk in the butter. Pour sauce into serving dish.
Slice tenderloin on the bias and place on top of the black cherry sauce. Serve immediately.
