Mix flour with salt for the dough. Add butter. Gradually mix up the curd cheese and knead it to a smooth dough. Wrap the dough with a plastic film and let it cool down in the fridge for minimum one hour.
For filling. Wash onion, carrot, pumpkin and leek, cut them into thin pieces. Fry them shortly with olive oil in a pan. Let the mixture cool down a little. Mix it up with curd cheese, add salt and pepper.
Roll the dough 1cm thick and cut it to the square pieces with 9x9cm size. Put in the middle of every dough piece one tablespoon of filling. Fold it to a triangle and press the edges with a fork.
Cook the dumplings in a steam cooker with 100% humidity for 25 minutes or in a cooking pot with a generously salted water.
For decoration: peel onion. Cut onion and pumpkin into small cubes and fry them with olive oil. Serve dumplings with onion/pumpkin cubes, cheese and some melted butter.