In a medium bowl, use your hands to mix together the coffee, chilli powder, paprika, salt, brown sugar, sugar, garlic, cumin and cayenne pepper until there are no clumps.
Pat the brisket dry with a paper towel; rub it with half of the coffee cure, massaging all the spices into
the meat; repeat with the remaining cure. Place the meat on a large plate, cover with plastic wrap, and marinate in the refrigerator for at least 2 hours.
Place the brisket on the centre rack of a smoker, fat-side up, under dry, indirect heat. Smoke for 12 hours at a steady temperature of 110°C/225°F, or until internal temperature reaches 85°C/185°F in the thickest side of the brisket. Open the door of the smoker and let the meat rest for 30 minutes, until the internal temperature rises to 88°C/190°F.
Transfer the rested brisket to a cutting board; cut into thin slices. Do not trim away the fat cap before serving.