Fill a large saucepan with water and add a little salt, the prepared onion, the bay leaves and the allspice grains. Let everything cook for about 15 minutes.
In the meantime, roast the flour in a saucepan until it is light to medium brown. Be careful, the flour burns quickly.
Remove the onion, bay leaf and allspice grains from the finished stock.
Mix the browned flour with two spoonfuls of the stock and stir everything through a sieve into the large stock pot until it is a sauce. Season with a little salt, vinegar and sugar.
Melt the butter in a saucepan and then add to the sauce. Season again with sugar, salt and vinegar. If the sauce is too runny, add a little more brown sauce thickener.
Now carefully beat the eggs into the pot and stir so that they don`t stick to the bottom. Poach until egg white is set.