Parry the cooked beef and cut into 2mm thin, bite-sized slices.
Melt the butter in a flat casserole dish, spread the meat slices over it and bake in the 220 ° oven for 10 minutes, turning once. Finally, drizzle the juice from ½ to a whole lemon over it.
Wash the zucchini, cut into 3mm thick slices and blanch them in boiling salted water (just covered) for 8 minutes so that they are soft but not yet translucent. Then drain well.
Whisk the eggs, stir in the sweet and sour cream, salt, pepper and plenty of nutmeg. Finally add the grated cheese.
Gently fold the drained zucchini slices into the egg and cream mixture. Gently pour the whole mixture onto the meat and bake the oven dish at 200 ° C for about 15 minutes. The mass rises and should brown a little.
Variations:
3 tablespoons of fresh tarragon leaves instead of nutmeg. Or red pepper, finely diced.
You can also vary the cream: some of the cream can be replaced with milk, for example, or you can only use sour cream.