Cut the zucchini into 2 or 3 parts and carve them out, leaving their bottoms whole. Salt them and leave them to drain a little. Chop the insides finely. Heat oil and fry the finely chopped onion and leek. Add the insides and fry it as well.
After about 10 minutes, add the washed bulgur along with 2 cups of water, salt, black pepper and the curry powder. Let saute until the bulgur boils, stirring periodically. Fill the zucchini with this stuffing. Arrange them in a greased tray, and if you have filling left, spread it around the zucchini.
Top with a trickle of oil. Add some hot water to the tray and put it to bake in a moderately heated until the water evaporates.
Serve the zucchini stuffed with bulgur with chopped dill and yoghurt, if desired.