Chop the sauerkraut and put it to sauté in some of the oil until soft. Chop the leeks finely and sauté them in a separate container with the remaining oil. Add salt to taste and optionally add a little black pepper.
Grease a tray, take 2 phyllo pastry sheets at a time and start arranging them, while greasing them with a little oil and alternating between a stuffing of sauerkraut and stuffing of leeks - phyllo pastry sheets, sauerkraut, sheets, leeks, etc.
Top off with 2 sheets, cut the celebratory pastry into large squares, pour about 1 cup of water over it and sprinkle it with oil again. Put it to bake in moderate oven to a nice redness.