In a large saucepan, put some previously peeled and chopped potatoes Chopped into not very large pieces so they cook before We are going to cover them with enough water to cover them completely Then we heat this water and once it has reached the boil we are going to let them cook for about 20 minutes With this potato we are going to make a puree and knowing in advance how it is the case we can peel it raw which is easier than already cooked and we can also chop it so that it cooks very well inside and then to be able to crush them without problems We do not add salt, the salt will go at the end. while it is cooking we are going to prepare a simple but delicious sauce In a frying pan put a little bit of oil and heat it over medium heat When it is hot, add two onions cut into thin strips to the onion yes yes we add a small pinch of salt and another freshly ground black pepper We stir while we let the onion cook for about 10 minutes we do not want it to take color simply leave it half done so that it is somewhat translucent, but also al dente inside, that is to say half done With 10 minutes of enough cooking. After this time we add 200 grams of crushed tomato and a tablespoon of dried oregano if you don't have oregano you can substitute it with dried rosemary The flavor changes, but it will give it a fetid touch anyway We integrate these new ingredients and let the whole thing cook again for another 10 minutes more, always over moderate heat without touching the temperature of the fire After this time the potatoes will be cooked and the sauce is ready but before going for the potatoes we are going to add about 500 grams of canned tuna here and now yes that we are going to take a ladle of the broth where the potatoes have been cooked, pay attention to this fact This broth, apart from the taste of the potato, also has starch , a starch that will help our sauce to bind better to each other Apart from giving it flavor, of course So we added it. We could even add two or more ladles of the broth. Now we turn off the heat, integrate all the ingredients together and that's it, we have the sauce done . Now it's time to give the potato a good slipper... it's your turn for potato! We have it in a bowl drained of all the cooking water First of all, we add the touch of salt that it needs We add it here and not during cooking because here we better control the amount that we add We also add your freshly ground black pepper And added these two condiments We simply mash it with the help of a potato press or a simple fork it doesn't matter, whatever you have at home The point is to mash it well until you make a simple puree with the potato, but the result is In a mold suitable for oven we are going to put a few ladles of the mashed potatoes that we have just prepared. With the same spoon we are going to press it and place it as a base in the mold The idea is to crush it and compact it well so that later it supports the ingredients that we are going to add on top Once we have the base of the mold well covered with puree we are going to go placing on this base as many tablespoons of the tuna sauce that we have just prepared and the same, we spread them over the entire surface of the mold so that it covers the entire potato base Now we return to cover this layer of tuna with more mashed potato And again with another layer of the tuna sauce So until you run out of all the ingredients you could even continue making more layers, if it is to your liking or if your mold is narrower and allows more layers To me, in my case, I already the ingredients have run out , it is what it is! so I just sprinkle with some grated cheese The cheese of your choice. A suggestion, if it is a strong cheese, better A cheese that adds a lot of flavor to our Manchego and Diazabal-type dish, even Roquefort or a mixture of several. I leave it entirely up to you, cooking has a lot of science but also a lot of art. The case is to cover the last layer with this grated cheese And now, baked with all of it. We put it at 220 degrees centigrade and as the ingredients are already cooked it does not require much cooking 10 minutes, until the cheese gratin And with all this done we already have ready a potato and tuna cake that is reminiscent of a lasagna but creamier due to to the texture of mashed potatoes a cake that is... Pure Ambrosia!
