| 2 sticks butter | 1 cup flour |
| 4 cups milk | juice of 3 lemons |
| 2 tsp. tarragon | 1 tsp. salt |
Make a roux of the butter and flour. Warm it slowly in a saucepan, adding the milk and stirring. Very slowly add the lemon juice. Add the tarragon and salt, and stir until thickened.