Remove peel from potatoes and cook in salted water.
Drain and steam the potatoes.
Press through a potato ricer, season with salt, pepper and nutmeg.
Sauté finely chopped shallots and chopped olives in olive oil.
Rinse leek, dice finely and sweat briefly.
Extinguish with 1/16 L cream.
Add quantity to potatoes form. Cut basil into strips and add.
Add feta cheese to the mixture.
Season with pepper, salt and nutmeg.
Place puff pastry on floured surface and cut into 18 x 10 cm rectangles.
Cut rectangles crosswise.
On each piece, mold 1 tbsp. of filling and roll up away from the wide side toward the tip.
Carefully bend on top into the shape of a croissant.
Stir egg yolk and 2 tbsp. cream.
Brush the croissants with the mixture and sprinkle with coarse sea salt.
Bake in oven heated to 180 °C for 15 to 20 minutes until golden brown.
Serve the potato-porridge croissants on a salad, garnished with a little sour cream.