First of all boil some water and boil the diced potatoes. If you diced them as a normal game dice it will take you 15 to 20 minutes. Depends on your stove. Once baked enough drain the water and leave the potato dices cooling.

Clean the fresh salmon fillet from fish bones, and cut it into dices (throw the skin), once done put it inside a bowl and fill de bowl until you cover the salmon with lemon juice. It has to be fresh squeezed. The lemon will cook the salmon, leave it these at least 30 minutes. (you will see the colour change as soon its baking) Its like sushi but the acid of the lemon will cook it.

Chop the onion tiny pieces and do the same as with the salmon, put them in a bowl and cover them up with the lemon juice. 15 minutes at least.

At last drain the lemons juice, take out the salmon from its bowl and the pieces of onion. Mix the salmon with the onions, add the potatoes dices (these have to be cool enough to not cook our fish we want a steak tartar not a low cooked salmon)and add the dices of avocado. Mix it all together and decorate with agar agar weed and chives, or with what ever you like (mayonnaise, eggs, some more avocado...)