Preparations:

Slice the meat into thin strips and season with salt & pepper then coat with the soya flour. In a frying pan, melt 2 tbsp butter over medium heat until it foams then fry the meat for several minutes. Add stock and keep stirring till stock thickens, add mushrooms and onion and stir till smooth. Return meat to pan, toss well and simmer in sauce for several mins. Add sour cream and heat but dont boil. Serve with fresh dill over top.