Step 1

Place olive oil, balsamic vinegar, garlic, brown sugar, thyme, dry mustard, and paprika into a food processor and blend. Pour marinade into a zip-top bag, add pork tenderloin, and marinate in the refrigerator for 24 hours.

Step 2

Preheat the oven to 250 degrees F (120 degrees C). Transfer pork and marinade into a Dutch oven.

Step 3

Bake in the preheated oven for 3 hours.

Step 4

Remove pork from Dutch oven and set aside on a plate, reserving drippings in the pan.

Step 5

Heat drippings in the Dutch oven over medium heat on the stovetop. Add sherry and deglaze the pan, making sure to scrape up any stuck-on pieces with a wooden spoon.

Step 6

Mix cornstarch and water in a separate bowl until completely mixed; add to sauce in the pot. Bring to a simmer and cook until thickened, about 15 minutes. Slice pork tenderloin and serve with sauce on the side or poured on top.