I do something similar ...
Cut spuds in one inch cubes into the heavy duty foil (spray PAM first) - then do the same with onions - (I like the onion pieces quartered but the wife doesn't - adjust as needed). Add your salt, pepper, garlic powder (not garlic salt) then add butter on top so the spices filter down as the butter melts.
What the heck is GrillMates Montreal Steak Seasoning? (well - steak seasoning! DUH!) OK - I looked it up - sounds great!
I'm gettin' hungry now ... it's all your fault!!
