For the short pastry, place flour, 1 egg, fat in flakes and salt in a mixing bowl and knead with the dough hooks of the hand mixer. Then knead again with your hands to a smooth dough and cover and leave in a cool place for about 30 minutes.
In the meantime, wash and peel the asparagus and cut off the lower woody ends. Clean the carrots (leave a little green if you like), wash and peel them. Put asparagus and carrots in boiling salted water and cook for 10-12 minutes.
Then carefully lift it out of the water and let it drain well. Place on a tea towel and pat dry slightly. Roll out the short pastry into a circle (approx. 32 cm Ø) on a floured work surface.
Place in a well greased tart tin (26 cm Ø, edge height 4 cm) and press the edge down. Prick the base several times with a fork. Refrigerate again for about 10 minutes. In the meantime, put the sour cream and the remaining eggs into a mixing bowl and mix well with the whisks of the hand mixer.
Season with salt, pepper and nutmeg. Put carrots and asparagus in the form on the dough. Pour the egg custard over the dough. Bake in the preheated oven (electric: 200 °C/ gas: level 3) for approx. 50 minutes on the lowest rack.
If necessary, cover after half the baking time. Remove from the oven and serve garnished with chervil as desired.