2 Tb. butter
2 Tb. flour
1 c. thin cream
Salt and pepper
Juice of 1 lemon or 1 Tb. vinegar
Melt the butter in a saucepan, stir in the flour, and continue stirring
until the two are well mixed. Add to this the thin cream and stir until
the mixture is thick and boils. Season with salt, pepper, and the juice
of the lemon or the vinegar.