While many Filipinos prepare kilawin to enjoy a booze, I love it with or without alcohol. As a matter of fact, I even eat it with rice, especially during summer when it is too hot to cook nor to eat hot foods.
Here is how I prepare it basing on my Nanay's method, plus adding more veggies and less hot peppers.
Ingredients and Procedure:
Tuna steak (I bought 2 steaks, about 1/4 pound total), cut into bite-size pieces
vinegar (I used Datu Puti cane vinegar; enough to submerge the fish)
Leave in the fridge for 30 minutes, after which, drain and squeeze gently to remove excess vinegar.
Meanwhile, chop the following must-have spices:
fresh ginger (thumb-size)
onion (medium size)
Add a dash of red pepper flakes (siling labuyo, chopped, if you have), depending on your taste
bell peppers, diced (I love these here)
Squeeze 1 whole lemon (My substitute for kalamansi) and remove the seeds.
Mix everything together, sprinkle the lemon, add salt and ground black pepper to taste, mix again, then let sit overnight (I like it overnight so that the lemon will fully "cook" the fish flesh. I do not want it overcooked, though, as it tends to be crumbly. I guess the size of the pieces matter. I prefer the size of the pieces to be about 1/2 inch by 1 inch by 1 inch. Any thinner and it will be "overcooked;" any thicker and it will be undercooked (with the inner flesh still looking pink, which I do not prefer. Others may prefer it that way, though, but I am no sushi lover.)
I prepared just a little amount because I expected only myself to eat it. To my surprise, my older son liked it as well, and remembered that he has had it before.
I had my FIL taste one prepared by my friend, with pieces quite thick so the inner part was not "cooked," and he could not stomach it. I could, but I really would prefer the "cooked" version.
I remember in Kamayan Restaurant, they serve the kilawin quite raw even on the outside (perhaps only mixed the the lemon-spices the moment the order was made), and I really could not take it.