I got this idea from a friend a while ago and I've been recycling it for many years. I can be cooked on the grill at medium heat, or it can be roasted in the oven. I like the grill version for summer!
Buffalo Pork Tenderloin
1.5 - 2 lb pork tenderloin
1 can/bottle beer
1 bottle buffalo wing sauce (not hot sauce)
Preheat grill to 375F. Place the tenderloin on a large foil sheet and fold the edges into raised corners (like a dish or bowl). Pour beer over pork, about 1/4 inch in foil. Pour some wing sauce over the pork so you can't see through it. Grill for 45 minutes, or until 165F inside the pork. Baste with beer followed by wing sauce, as needed. Remove and serve warm.
The beer keeps the tenderloin so moist and the wing sauce makes a nice coating on the edge. Barbeque sauce also works pretty well when we get tired of Buffalo flavor (hey, it happens... rarely). Serve with summer veggies like grilled zucchini and yellow squash.