Preheat oven to 425°F. In a medium bowl, combine biscuit mix and water; stir until blended. Drop 5 equal portions onto a lightly greased baking sheet. Bake until tops are crispy and golden brown, about 11 minutes. Meanwhile, place ham in a cast iron skillet over medium-high heat. Cook until both sides are browned, about 8 minutes. Pour coffee into skillet to deglaze pan, stirring to make sure any particles that have stuck to the skillet are loosened. Reduce heat to a simmer, cover, and cook for 5 minutes. Split biscuits in half and place a slice of country ham between halves. Dip in the red eye gravy.