Yellowfin Tuna has a medium-mild flavor with very firm texture. The flesh is deep red while raw. Fresh Yellowfin Tuna is delicious when grilled or seared. Brush the fish with olive oil, and sprinkle with salt and pepper. Grill each side for only 2 to 2 1/2 minutes. The center should be raw, like sushi, or the tuna will be tough and dry. Allow to rest for 5 to 10 minutes and serve.