Knead the flour with half a teaspoon of salt, the butter and the egg into a shortcrust pastry, add a little water if necessary and wrap the dough in foil and put it in the fridge for half an hour.
Peel the kohlrabi, cut into slices and then into pieces. Cook in boiling salted water until just under cooked, remove with a slotted spoon and drain well.
Wash the leek, cut into rings and add to the kohlrabi, as well as the diced ham and mix everything together.
Preheat the oven to 180 degrees top and bottom heat.
Grease and flour the tart pan, roll out the dough, place it in the prepared pan and press up a small edge. Prick the base several times with a fork then prebake for about 5 minutes.
Then spread the ham and vegetables mixture on top. Mix the two eggs with milk, cheese, curry powder and possibly also salt and pepper and pour this over the tart.
Put the tin back in the oven and finish baking the tart in about 35 minutes.