Pre-cool the blast chiller with the pre-cooling function at -30°C.
Freeze the tuna slices at -18°C with the automatic program - freeze - fish - slices/fillets.
Preserve in the freezer for at least 96 hours.
Continue the procedure by selecting the defrost by weight selecting the tuna weight.
Clean the artichokes and soak them in a cold water and lemon bowl. Cut the stem up to 2cm to the leaves and remove stray leaves only keeping the sweet part of the artichoke.
Discard the external layer of the stem and cut the artichokes in half taking out the internal bitter part. Prepare the citronette by squeezing one lemon and emulsify it with a little bit of olive oil. Flavour it with salt and let it rest.
Cut the artichokes in julienne strips and season it with half the citronette. Take the tuna fillets and dip them in black and white sesame seeds on both the sides. Warm up a non-stick pan, place the tuna fillets and cook them on high heat for 1 minute. Turn them around and keep cooking for one more minute. It's possible to keep the cooking a bit longer based on your taste. Once cooked take out the fillets and cut them up in slices immediately and season with the remaining citronette.
Match it with the artichokes salad.