Lipton Onion Soup mix is fantastic in many recipes.
My favorite is to slice potatoes into 1/4 inch thick slices. Sprinkle the mix between the slices and re-assemble the potato. Smear the top with butter and wrap tightly with 2 layers of foil so you can flip them if need be.
Cooking time depends on temps but since they're wrapped in foil, they can sit in your smoker for quite some time without drying out.