Yellowfin Tuna has a medium-mild flavor with a very firm texture.  Compared to other Tunas it is less flavorful than Bigeye but more flavorful than Albacore.  The flesh is deep red while raw is often used for sashimi, and is best not cooked well-done as it loses flavor and becomes like cardboard. Source: Chefs-Resources

Fresh Yellowfin Tuna (Ahi) is a delicious fish that lends itself best to grilling or searing cooking applications.