Boil or tier steam the potatoes
I like to leave the skin on, if you want to peel them, do it before this step. Halve them.
Cut each half into fourths lengthwise and place them on a baking tray with wax paper and some flour so that they won't stick
Sprinkle them with thyme, bay leaves, cracked pepper, salt and sunflower seeds oil. Bake at 180C until crispy outside and soft inside, the amount of time will depend on how much you precook them.
Leek purée: cut and sauté the leek, then purée it with a blender. In a small pot melt the butter and stir in the flour, cook for few minutes then add milk and puréed leek. Stir until thick enough.
In a nonstick pan heat up some sunflower seeds oil. When sizzling hot throw in your tuna. Be ready to be quick, cook for about 30-40s per side.
You can see the color changing from red to pinkish
Take them out and place them on a cutting board
Using chopsticks to hold the tuna without spoiling the piece, slice it up quickly with a sharp knife, be careful as it's very tender.
Scoop the leek purée at the center of the plate, surrounded by the roasted potatoes. Place the tuna slices at the center and sprinkle with chopped parsley and the smoked paprika.