Mix egg yolk, milk, flour and a pinch of salt to form a smooth dough and let it swell for about 10 minutes.
Peel the onions, dice finely and sweat in 1 teaspoon oil until translucent. Add the tomatoes and let simmer for about 5 minutes. Season with salt and pepper.
Wash and finely chop the herbs. Clean and chop the mushrooms. Now beat the egg whites until stiff and fold them into the swollen dough together with half of the herbs.
Heat 1 teaspoon of oil in a non-stick pan and fry the mushrooms until golden brown. Now pour in the dough and bake until golden yellow on both sides. Then tear into pieces with 2 forks and bake briefly.
Stir the remaining herbs into the tomato sauce and serve with the pancakes.
Good eaters should increase the quantities given a little.