Peel 1 onion, wash the tomato, halve both. Heat the oil in a pot. Sauté the onion in it. Add tomato, approx. 3⁄4 l water, 1 1⁄2 tsp. salt, peppercorns and bay leaf. Bring to the boil, cover and simmer for about 5 minutes. Wash the meat and simmer covered in the stock at low heat for about 20 minutes.
Finely chop the bread for the crust. Grate cheese. Wash and chop parsley. Mix everything.
For the sauce, lift the meat out of the stock and let it cool down a little. Sieve the stock, collect and measure 150 ml (use the rest of the stock for other purposes). Peel 1 onion and chop finely. Heat 2 tablespoons of butter in a pot and sauté the onion. Add flour and sauté until light brown. 1⁄4 Add l stock, bring to the boil and simmer for about 5 minutes. Stir in mustard and crème fraîche. Season to taste with salt and pepper.
Pluck the meat and put it into a greased casserole dish. Spread the sauce and breadcrumb mixture over it. Place 2 tablespoons of butter in flakes on top. Bake in a hot oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer) for 20-25 minutes. Serve with tomato salad.