Rhubarb rinse, clean and cut into 2 cm thick pieces. Mix flour, egg yolks, a little salt and whipping cream until smooth. Whip egg whites until stiff and fold in.
Heat clarified butter in a frying pan, pour in a ladle of batter. Spread 100 g of rhubarb evenly on top. Sprinkle with pistachios and toast over medium heat for 2-3 minutes until golden brown.
Toast 4 omelets, divide evenly on plates and bring to table sprinkled with brown sugar.
By the way: Did you know that clarified butter is obtained by extracting water, milk protein and lactose from butter?