Should you pan sear tuna with oil or butter?

You put your pan on the stove and get it good and hot first and add only a very little bit of olive oil.

Cook the tuna on the first side 2-3 minutes then turn over and cook another 2-3 minutes on the other side..

Cook longer if you want it more done. the 2-3 minutes on each side will still be fairly rare on the inside.

If you wanted to add a bit of flavor use salt and ground pepper, and use it to coat the top and bottom where you are searing it. The moisture of the tuna will hold the seasoning in place.

I like it VERY Rare, I only do 2 minutes tops on both sides, but it depends on your own tastes, so you may want to try to experiment, because you can't "un-cook" it! :)

(but you can always put it back on for another minute or less)