Knead flour, butter, salt, 1 egg and approx. 1 tbsp. cold water to a smooth dough. Wrap the dough in foil and chill for about 30 minutes. Wash the herbs, clean if necessary and shake dry. Cut chives into small rolls.
Pluck parsley leaves and dill flags. Set some leaves aside for garnishing. Chop the remaining herbs finely.
Grate cheese. Wash lemon hot, grate dry and grate half of the peel thinly. Whisk cream cheese, sour cream and 3 eggs, season with salt, pepper and nutmeg. Add herbs and cheese. Wash and clean the tomatoes.
Roll out the dough on a floured work surface in a square shape (approx. 25 x 25 cm). Line a tart mould (approx. 23 x 23 cm) with lift-off bottom with the dough. Fold the protruding edges inwards and press down firmly.
Pour the cream cheese and egg mixture into the mould. Spread tomatoes in the middle. Bake the tart on the lower shelf in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 30 minutes.
Remove the tart from the oven and remove from the mould. Garnish with the remaining herbs and serve immediately.