A favourite rub recipe of mine is a coffee rub. Preferred steak for this is T-bone, but you can use anything really. This will make enough for four steaks.
Mix all ingredients together in a bowl.
1 tablespoon brown sugar
1/4 teaspoon ground red chilli flakes
1/2 tablespoon freshly ground black pepper
1 tablespoon sea salt flakes
15 grams coffee grounds (espresso grind)
1/2 tablespoon granulated garlic
1/2 tablespoon smoked paprika
1/2 tablespoon ground oregano
1/2 tablespoon coriander seeds, crushed
Apply liberally to steak and pat. I've tried the cast iron pan, but a bbq is better for this. You don't need to get a crust given you have the rub on. Let steaks come up to room temp and onto the fire. Again, you won't need stinking hot as you'll just burn the rub.