Give Denis Seafood a try. They have two locations, one at 12000 Westheimer, near Kirkwood and one up on Katy Freeway near Bunker Hill. I cannot speak knowledgably about the one on Katy Freeway, but wife and I really, really like the Westheimer location, and we eat there at least once a month.
Tuna is usually offered on their Fresh Today chalkboard specials, and you can order it in several different ways. Also, not sure if what you spend is important to you, but pricing at Denis is among the lowest I've found for quality seafood. Their pricing is usually about 3 or 4 dollars less on each plate than the big chains (Landry's, Pappas)
Also, excellent desserts! (leave room for their huge Bread Pudding -- yummmmm!)