In a frying pan over a medium heat, warm half the oil and add the beef. Add the mustard powder and horseradish and cook and stir for 2 to 3 minutes until browned, then remove from the pan and set aside.
Add the remainder of the oil to the same pan, along with the onion, mushrooms and garlic and fry for 5 to 6 minutes.
Add the wine and season with salt and pepper. Add the yoghurt and cream cheese. Combine all the ingredients into an ovenproof dish then cover.
Bake in the preheated oven for 45 to 60 minutes until the flavours have developed and the steak is tender. Remove from the oven and serve.