Beer soup (biersuppe)

4 tbs butter
2 tbs flour
4 cups beer
Pinch of salt
Pinch of nutmeg
Pinch of ginger
Pinch of cinnamon
4 egg yolks
1 tbs sugar
1 cup dry white wine
Grated peel of 1 lemon

1. Melt butter in a large saucepan. Stirring constantly to avoid lumps, gradually blend in flour and cook over moderately low heat until the flour is golden.
2. Still stirring, slowly pour in the beer. Add the salt, nutmeg, ginger and cinnamon. Simmer gently for 20 minutes. While beer is simmering, beat egg yolks well in a bowl. Add sugar, then beat in white wine and the grated lemon peel, Drop by drop, beat 1/4 cup of the hot beer into the egg mixture.
3. Gently stir egg and beer mixture into the remaining hot beer. Heat through, making sure the soup remains below the simmering point. Taste and correct seasoning, if necessary.