In a small bowl, combine 3 tablespoons of brown spicy mustard with 2 tablespoons each of ground coffee, paprika, granulated garlic, and minced onion.
Add 1 tablespoon each of brown sugar, black pepper, and salt to the bowl and mix until well combined.
Once you have mixed all of the ingredients together, take the steaks and pat them dry.
Spread the rub evenly over both sides of your steak, pressing the rub into the meat with the palm of your hand to ensure even coverage.
Let the steak sit for at least 30 minutes before grilling it on your pellet smoker.
Cook and enjoy your coffee-rubbed steak!