Coffee Crusted Barbecue Beef Ribs with a Versatile Rub

Name: Coffee-Crusted Barbecue Beef Ribs (with a Versatile Rub)
Ingredients: 1/3 cup dark roast coffee beans; 1/4 cup black peppercorn; 4 tablespoons sea salt, plus more for serving; 4 tablespoons hickory smoked sea salt; 2 tablespoons smoked Spanish paprika; Olive oil; 5 pounds bone-in beef ribs (approximately 4 racks); Dijon mustard, for serving (optional)