Here is the proper way to cook a fresh piece of tuna: Get a skillet. Get it nice and hot, add a little oil. On the other side of your kitchen, place your tuna fish on a clean plate. Lift the plate and point it at the hot stove. Count to three. Cross the room, shut the burner off, then return to and eat your tuna.
This is not the method followed at Churros Calientes, sadly, much to the detriment of the sandwich. There is a certain tragedy inherent in tuna, as I have noted before, and that’s in a well-cooked piece. Overcooked, the pathos becomes too much to handle. This was a fine piece of meat, and it gained much from a flavorful herb/spice/vinegar marinade. I really wanted to like this sandwich. But all flavor played second to the dry, mealy tuna, the result of much too much heat. There’s no saving something like that. An inherent tragedy is one thing, but a willful one is something very different.
(Though it is outside the purview of this blog, I would like to note that the churros at Churros Calientes are phenomenal. Really stellar churros, well worth going out of your way.)