For the yeast dough, mix the wheat flour, durum wheat semolina and sea salt thoroughly in a large bowl and form a well in the middle of the flour. Mix the yeast with the sugar in a beaker and gradually add the lukewarm water until the yeast has completely dissolved. Add the yeast to the flour in the well and let rise for 15 minutes.
Add the olive oil and best knead the ingredients with a hand mixer for 5 minutes to form a smooth dough. Let the yeast dough rise in a covered bowl for at least two hours.
For the topping, dice the peeled zucchini and vegetable onions.
Heat a large pan and leave the diced ham in the pan without adding any fat. Then add the zucchini and onions, season with the ground caraway seeds and the grained vegetable stock, pepper and salt and sauté the vegetables until translucent.
Remove the pan from the heat and let the vegetables cool.
Knead the dough well again, roll out on durum wheat semolina and place on a large, deep baking dish greased with margarine. Pull the dough up along the edges of the baking sheet.
Let the yeast dough rise again for a quarter of an hour in the oven at 30 to 40 ° C top / bottom heat.
Mix the eggs with the sour cream and sour cream with a whisk in a large bowl. Season with freshly grated nutmeg, pepper and salt. Add the cooled zucchini, onion and ham mixture, mix everything together and distribute evenly on the yeast dough.
Preheat the oven to 200 ° C top / bottom heat and bake the zucchini-onion cake for 30 to 35 minutes.