Fluffy Vanilla Custard Floating In Cranberry Kisel

Wash and crush the cranberries.
Place crushed berries into a saucepan and add sugar.
Add 1.8 l boiling water to the saucepan.
Heat until bubbles appear, then bring heat to medium low and keep the mix boiling gently for about 10 minutes.
In the meantime, dissolve the starch in 100ml cold water.
When cranberry mix is ready, pass it through a sieve to get rid of berry skins and return the hot juice into the saucepan. Keep it on medium-low heat and slowly pour in the starch mix. This is the crucial moment: you've got to keep stirring kisel vigorously as you add more starch, in order to avoid lumps.
After you've added starch, bring kisel to boil.
Let cool.
Making the custard
In a bowl, combine flour and 250ml milk.
Beat the mix using a fork until it's thin and runny like a crepe batter.
Beat egg yolks with 1/4 cup sugar and 2/3 tsp vanilla sugar until pale. Set aside.
In a saucepan, bring to boil the remaining milk.
As the milk starts to boil, add in the milk&flour mix while stirring.
Add in egg yolks&sugar. Keep stirring vigorously to break up large lumps.
Simmer the custard for a couple of minutes, stirring all of the time, until it thickens. Set aside.
Add remaining sugar to cooled egg whites and whip them until thick and stiff.
Use a blender to break up small lumps in the custard, if any.
When the custard is smooth and creamy, add in the whipped egg whites and stir together gently.
Leave to cool.
Fill small bowls with kisel, then gently add scoops of custard.