I use two pieces of tenderloin put together 69 style. Cut each piece lengthwise to create space for stuffing. Stuff with whatever: cooked sausage, basil leaves, pesto, mushrooms, cooked bacon.....

 

Tie with at least 5 pieces of string. Rub with oil, seasoning...

 

Cook:  brown in pan then bake; smoke; grill. Go for internal temp of 135

 

 Above is from a friend who is a better than average cook/chef.