Heat up butter or oil or a mixture of both in a casserole;
Place the filet mignon strips in the casserole over a medium flame and brown on all sides;
Add the whole onion, the shallots, the unpeeled garlic clove and wait 2-3 minutes while stirring; add the cubed carrots and potatoes, the mushrooms;
Once everything is well cooked, add the curry powder, stir quickly and deglaze with the white wine;
Add the green pepper and the soy sauce;
Cover and cook for 30 to 40 minutes, or until the carrots and potatoes are fully cooked;
Cut the cauliflower florets into similarly sized pieces and add them to a shallow pot, along with 2 cups of water and a pinch of salt; cook for 5 minutes;
Once the filet mignon is completely cooked, raise the heat and add the crème fraîche; let the sauce reduce for 5 minutes, stirring all the while.