Every week, SO and I usually enjoy a nice seared tuna with scallops. It seems that the texture of the finished product varies somewhat each week and sometimes feels tough as if it's been denatured too much prior to searing (quick 45-1 minute each side). My marinade usually includes garlic, ginger, soy sauce, rice wine vinegar and I only marinate for 10-15 minutes on each side for both the scallops and the tuna. I'm not really looking for a new marinade as we love this mixture but of the ingredients it seems to me that the likely offenders might be the ginger or vinegar. Any other ideas? Should I just add them after it marinates as we use the remaining liquid as a sauce?