Proceedings
Mix the rye flour and wheat flour, then knead with the oil, egg, milk and salt until you obtain a smooth dough. Wrap the dough in a sheet of cling film and let it rest for at least 30 minutes.
For the filling, melt the butter in a pan and brown the finely chopped onion, then let it cool. Add the ricotta, potatoes and chives, and season with salt and pepper. Among the alternative fillings are spinach or sauerkraut.
Roll out the dough with a pasta machine to obtain a thin sheet and place the ricotta filling in small mounds, spaced apart. Brush the edges with water and lay a second sheet of dough over the first, cut out round ravioli - called tirtlen - and seal the edges well.
Heat the fat and fry the tirtlen, at a temperature between 180 and 200 degrees, on both sides, for about 2-3 minutes. Then dry them thoroughly with kitchen paper towels.