Rinse the turkey schnitzel with cold water, pat dry and pat flat. Sprinkle with flour, salt, pepper and thyme. Brush with mustard and top with 1 slice of ham and 1 cucumber half. Now roll up the meat, pin it with a wooden skewer or wrap it with kitchen twine.
Peel and finely dice the onions. Wash the lemon with hot and pat dry, then rub 1 teaspoon from the peel and squeeze out the juice.
Now heat the clarified butter in a casserole and fry the roulades all over. Add the onions, vegetable stock, lemon juice and lemon zest and bring to the boil. Cover and stew the roulades over a low heat for 20 minutes.
In the meantime, prepare the frozen vegetables according to the instructions on the packet.
Lift out the roulades, keep warm and pour the sauce through a sieve into a saucepan. Stir in the sour cream and let the sauce simmer for about 5 minutes. Season to taste as needed.
Arrange the roulades with vegetables and sauce on plates and serve hot.