In a bowl combine the red miso paste, sake, & mirin. Mix well.
Place the salmon fillets in a plastic bag.
Pour in the miso marinade and shake well.
Place in the refrigerator for 4 hours.
If you are using a gas grill set the temperature to medium. If you are using a charcoal barbeque get the coals to the point that white ash is showing and the coals are glowing and are spread out in an even layer.
Remove the salmon from the plastic bag and towel dry. Rub both sides with olive oil. Place some olive oil on a paper towel and carefully rub down the hot grill so that the salmon will not stick.
Place the salmon on the grill. If you have skin on fillets place the skin side down first. Grill for 3 to 4 minutes.
Carefully turn the salmon over and grill for an additional 3 to 4 minutes. Remove and serve.