I make this quite often and I get lots of questions about it. So, here is the "recipe" ... I use that term lightly because it is so simple! I love to get tuna tataki at Sushi Gen here in Shreveport and one of my favorite pastimes is trying to mimic my favorite meals from my favorite restaurants. I started with my spin dip, modeling it after the amazing tip at the Oyster Bar [which they no longer serve!] and had great success. Since then, I've been able to recreate several recipes that I can make for less than going out on the town. [such a homebody]
Tuna tataki is served over pickled onions and fresh cucumber and with a sauce that is distinctively Asian, so I'm just showing the tuna prep/recipe only which will make it up to you how to serve it. I think that it is a super versatile protein [about 7g per oz - same as beef!] that can be incorporated into any style or palate. We put it over different salads, wrap it up with veggies, serve it as an appetizer when guests are over, dip into ginger sauce and eat with noodles for a heavier choice. So many options!
1 tuna steak - thicker the better, about 6oz
roughly 1 cup spice/herb mix of your choice
1 tbsp olive oil
medium sized tupperware
Fish have their own natural oil, so you won't need to dredge the steak in anything to get the spice mixture to stick. Mix your spices/herbs in the tupperware dish, add the tuna steak and press the mixture into all sides, covering the steak completely.
Get your pan nice and hot, you're going to want to have a good, quick sear on this. I add just a little bit of olive oil [tbsp or so] while it is warming. Sear the steak for about 2 minutes on each side. I think it is easier just to use my hands and start with the thin sides first, finishing with the broad sides. Tongs are helpful if you're new to the technique and silicon tipped tongs are best since they won't cut into the sides of the steak.
When you're done, place the tuna steak back in the tupperware [where your spice mix was], seal it and stick it in the freezer for about 45 minutes or if you're planning well in advance, a few hour in the fridge will have the same effect. Cooking it did will ensure the crust stays solid and the steak will slice beautifully.