Make an elastic dough from the flour, egg, salt and lukewarm water as described for the Apple Strudel, shape into a ball, cover and rest for 30 minutes.
Shred or grate the cabbage thinly, sprinkle with the 1 tsp salt, leave for a few minutes, then squeeze out the excess moisture by hand.
Sauté the finely chopped onion in the lard until translucent, add the squeezed cabbage, sugar and pepper, and cook covered over medium heat for 15-20 minutes, until the cabbage is soft and glossy.
Remove the filling from the heat and let cool completely.
Stretch the dough paper-thin on a floured tablecloth, as in the Apple Strudel.
Scatter the cooled cabbage evenly over one half of the dough, and drizzle with a few drops of lard.
Using the tablecloth, roll up tightly, tuck the ends under, and place on a greased baking tray.
Brush the top with melted lard, and bake in a 200°C preheated oven for 35-40 minutes, until the crust is golden brown and crisp.
Serve lukewarm or cold, sliced.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.