Combine Sautéed Onion ingredients in skillet and place on grill
Cook a couple minutes
Remove from heat
Combine Steak Butter ingredients in same skillet as the onions were cooked
Cook 2 - 3 minutes
Dip steaks into butter and season both sides with pinch of salt and pepper
Place on direct heat side of grill for 2 minutes per side
Move to indirect heat side and cook for 10 - 12 minutes
Move back to direct heat for 1 - 2 minutes
Let meat rest for 5 - 10 minutes, tented before cutting
Melt stick of butter in skillet
Brush hoagie buns with melted butter and place on indirect heat side
Cook for a couple minutes until browned
Put dijon mustard on hoagie
Add 1 slice provolone cheese
Slice steak into strips and top provolone
Add some onions
Add 1 more slice provolone
Add fresh baby arugula
Cut in half and serve