I use a dry rub on the backstrap.

1 tbl. garlic powder
2 cups sugar
1/4 cup paprika
2-3 tbl chili powder
2-3 tbl cyanne powder
1/2 cup salt
2-3 tbl black pepper
2-3 tbl peppers (pizza kind)
2-3 tbl of cajun seasoning (use this instead of chili powder for different taste)

mix together
cut straps into about 6 inch longpiecesrub mixtureon meat vacuum seal over night.
slow cook on the grill till center of meat is 160degs. (med)
slice into thin pieces across the grain and enjoy.