We freeze the tuna for a week in the freezer to avoid the possible risks of anisakis. The day before preparation, we remove the tuna from the freezer and we let it thaw slowly inside the fridge. For the dressing, we chop half an onion and a clove of garlic in very fine brunoise.
Also chop the olives, capers and pickles into small pieces, stirring everything well so that it is distributed. On the other hand, cut the bluefin tuna with the knife into small cubes and reserve. In a bowl, We mix three tablespoons of soy sauce, a pinch of mustard, 1 drizzle of sesame oil, a little Perrins sauce and a few drops of Tabasco.
We pour the pickle mixture into the sauce and stir well to integrate all the ingredients. We test and adjust to taste adding what we consider best. We incorporate the chopped tuna and Mix with the other ingredients, stirring carefully so that the dice do not break.
Let the mixture rest for 5 minutes while we prepare the base on which we will serve the tuna tartare. At your choice you can put a wakame salad with sesame -as I have done-, you can cut a good tomato into cubes or concassé, or put a diced avocado base, although the mixture of tuna and avocado It is already a very hackneyed presentation, which can be tired.
We season the ingredients that we have decided to use as a base with a little salt and a good extra virgin olive oil and We serve the red tuna tartare on this base, using a plating ring. Remove the ring and decorate with sesame seeds.