Clean & trim the rhubarb (no peeling!). Cut the stems in pieces of about 8-9 cm; pick the red ones & set aside. You'll need 20 pieces.
Preheat the oven to 160° C w/ fan.
Slightly oil the tart form (if necessary).
Combine all the ingredients for the pastry in a bowl, roll up your sleeves & start kneading.
Roll out the pasrty between 2 sheets of cling foil & transfer the pastry into the tart form. Fill bottom & edges. Set aside.
Mix ricotta, eggs & sugar w/ an egg whip.
Pour the ricotta mess into the pastry.
Add the pieces of rhubarb & sprinkle vanilla sugar on top.
Let it bake in the preheated oven at 160° C w/ fan for about 50 min.
Let the tart cool down for about 10-15 min. Then transfer to a appropriate plate.