* rhubarb from the skin and cut into 3cm long pieces * water with sugar, juice of a lemon and rhubarb pieces in saucepan, briefly bring to a boil, cook at low temperature 3 minutes * rhubarb from the saucepan, cool and drain, collect the juices.
* Add the finely chopped strawberries to the stock, soften briefly, crush and pass through a sieve, the stock should be creamy, perhaps boil a little more, then set aside to cool * Separate the eggs
* Halve the vanilla pod and scrape out the pulp * Mix the egg yolks with the grande, vanilla pulp, Marnier whipped cream, the gravy and cornflour.
* Whip the egg whites with the powdered sugar to a single egg white * Add the whipped egg whites to the egg yolk mixture and mix well * Shape the rhubarb in a greased gratin dish * Spread the egg mixture evenly over the rhubarb until it is well covered * Preheat the stove to 170 °C and bake the gratin for about 15 minutes
The gratin should be served lukewarm, accompanied by vanilla or strawberry ice cream.