Prepare clean, boneless, skinless goose breasts and place in a covered dish or zip-lock freezer bag. Add enough buttermilk to cover. I like to add a couple of dashes of Worcestershire sauce to the buttermilk marinade. Allow to marinate in the refrigerator for 2 days. Turn at least once per day.
Prepare the dry rub recipe:
6 Tbsp ground coffee
2 Tbsp coarse salt
2 Tbsp paprika
2 Tbsp brown sugar
2 Tbsp black pepper
2 tsp onion powder
2 tsp garlic powder
1 tsp coriander
Combine all ingredients and mix thoroughly.
Rinse the breasts and pat dry. Cover all sides liberally with the dry rub. Allow to stand for 30 min to 1 hour before grilling for maximum flavor. Grill over hot coals until medium-rare. Do not overcook! Remove breasts from grill, cover with aluminum foil and allow to rest for 4 - 5 min before serving. Breasts will taste like tender filet mignon. Another option is to cut breasts into 2 equal medallions and wrap the edge with bacon before adding the dry rub - delicious!