In a large Ziploc bag, combine pineapple, lime, cilantro, hoisin sauce, sesame oil, ginger. Mix well. Toss tuna into bag and place into refrigerator for 1-2 hours.
Prepare grill by spraying with nonstick cooking spray and starting coals for high heat. Remove tuna steaks and lightly shake to remove excess marinade. Place tuna steaks onto prepared grill for approximately 4-5 minutes per side being extra cautious and prevent overcooking.