Clean, wash and cut the rhubarb into pieces. Bring 200 ml water, 50 g sugar and vanilla sugar to the boil. Simmer covered rhubarb for about 5 minutes. Mix juice and starch until smooth and stir into the boiling rhubarb.
Bring to the boil again and simmer for about 1 minute. Let the compote cool down, stirring from time to time.
Dice bread very finely. Bring butter, lemon zest, 25 g sugar and milk to the boil. Mix in bread and let it swell for about 15 minutes.
Separate two eggs. Chill the egg whites. Stir 2 egg yolks and 1 egg into the bread mixture. Grease 4 ovenproof moulds (approx. 9 cm Ø; 200 ml each). Spread the bread mixture in them and bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for 20-25 minutes.
Beat 2 egg whites and 1 pinch of salt until stiff, adding 50 g sugar. Take the pudding out of the oven. Spread some rhubarb compote on each. Spread the meringue loosely with a tablespoon.
Continue baking at the same temperature for 12-15 minutes. Serve with the rest of the rhubarb compote. drink tip: Earl Grey tea.