- Shape beef into 6 patties. 
- Heat a large skillet over medium – high heat, add butter and melt until it foams. 
- Add spring onion and garlic, sauté until softened, about 30 seconds. 
- Season beef patties with salt and pepper, and cook to the desired degree of doneness, turn once, set aside and keep warm. 
- In the same skillet, add and sauté the mushrooms until limp, then add to the warm beef patties. 
- To prepare the sauce, deglaze the pan with dry white wine. Reduce volume by half. Add Dijon mustard, heavy cream, tomato, and capers. Heat slowly until hot but do not boil. 
- Pour mustard cream sauce over beef and mushrooms