Step 1

Gently pat the beef slices thinner, trying to give them an oblong oval shape. (about 1/4 inch in depth). Season with salt and pepper. In a large skillet, heat a tablespoon of butter and a tablespoon of oil over medium high heat. Add the beef slices and fry until golden brown on both sides, turning once. Transfer the meat onto a place and put aside.

Step 2

If neccessary, add another spoonful of butter onto the skillet. Add flour and cook for a minute, stirring carefully. Now and the beef stock and stir, until you've got a thin gravy. Return the meat into the pan and simmer for 10-15 minutes, until the meat is cooked.

Step 3

When beef is tender, then use a slotted spoon to remove them from the pan and keep warm on a plate, covered with a piece of foil.

Step 4

Add the sour cream to the sauce, cook for a few minutes, then season to taste with salt and pepper.

Step 5

While the beef is cooking, prepare the onions. Peel the onions, halve lengthwise and then cut into thin slices. Melt another spoonful of butter and a spoonful of oil in a large skillet over medium heat. Add the onions and cook, stirring occasionally, until golden. This will take about 10-15 minutes.

Step 6

To serve: spoon the gravy onto a plate, top with a slice or two of beef and garnish with a generous amount of fried onions.