Tartare of avocado with crab and a tapenade olive paste wafer

Preparation 30 min
Cooking time 25 min (if you cook the crabs)
Ingredients for 4 persons :
4 avocados (count 3 big ones)
2 800 g crabs
3 red onions (2 nice big ones will be enough)
1 lime (I count 2 but it depends on the juice)
1 bunch of flat parsley
1 bunch of chives
Olive oil
Hazelnut oil
Cumin
Salt and pepper
For the tapenade olive paste wafers :
100 g of black tapenade olive paste
60 g butter
80 g flour
60 g freshly grate parmesan
1 egg white
Preparation of the crabs :
Step 1. Start cooking the crabs in cold water during 15 to 20 minutes depending on their size, strain and let them cool down.
Step 2. Remove the claws and the legs in order to extract the crab meat.
Step 3. Separate the shells and cut them in half then pick out as much crab meat contained in the mazes.
Step 4. Season the crab meat with tablespoons of hazelnut oil, salt and pepper, add some finely chiseled parsley.
Preparation of the tapenade olive paste wafers :
Step 1. Mix the tapenade with the softened butter, add the flour, the grated parmesan and the egg white.
Step 2. Spread on sulfurized paper or on a silicon sheet in long flat strips (careful not too fine otherwise the wafers will be very fragile) and cook for about 5 min in the oven preheated to 170° (adapt cooking time according to the oven).
Preparation for the raw avocado tartare :
Step 1. Cut the avocados in 2, remove the pits and dice up the inside flesh.
Step 2. Place the avocado in a salad bowl with half the lime juice, 1 table spoon of oil,1 pinch of cumin, salt and pepper-mix delicately.
Step 3. Dice up the peeled onions. Season with the remaining lemon juice and let sit until the onions become translucid violet.
Step 4. Then set aside 1/3 of these onions for the decoration and add the remaining 2/3 of the chiseled chives while keeping a few whole twigs of decoration. Mix this with the raw avocado.
Step 5. Place circles on the presentation places and spread a layer of tartare in these circles, then place the crab or shrimp and add the rest of the tartare.
Step 6. Pat down slightly and place in the icebox until serving time.
Step 7. Just before serving, remove the circles and decorate with a shrimp (if you choose to serve a shrimp tartare), twigs of chives and a tapenade wafer.
Step 8. To finish, make a line of chopped red onions to which you will add the remaining chiseled parsley.