Sift the flour into a large enough bowl and mix with the salt. Add the cold butter in flakes. Meanwhile, work everything with a kitchen knife until a crumbly amount is formed. Add the water, as cold as possible, and quickly combine everything together by hand to form a smooth dough. Wrap in plastic wrap and leave to cool for at least 30 minutes before use.
In the meantime, cut the cabbage into quarters and remove the stalk. Now cut the vegetables into strips as fine as possible. Rinse the spinach thoroughly and remove the leaves.
Boil well salted water. First blanch the cabbage strips for three minutes. Remove with a skimmer and drain well. Then add the spinach to the salted water form and over-wave for one minute. Drain and squeeze.
Butter a pie or possibly tart springform pan. Roll out the dough on a lightly floured surface and spread the pan with it, raising a rim of a good two inches. Prick the bottom regularly with a fork. Put the pan in the oven heated to 220 degrees Celsius on the second lowest rack and pre-bake the dough for twenty minutes.
Spread the cabbage and spinach evenly on the base. For the glaze, mix the eggs, the sour cream and the grated cheese.
Season with salt, pepper and nutmeg. Spread evenly over the vegetables and sprinkle this with the sunflower seeds.
Bake the quiche at a constant temperature on the under