Served this sauce enriched with beurre (butter) over a thick salmon baked in herbs, olive oil and a hint of lemon.
A heavy-bottomed, 6-cup enameled, stainless steel, lined copper, porcelin, or pyrex saucepan
2 Tb butter
3 Tb flour
Wooden spatula or spoon
In the sauce pan melt butter over low heat. Blend in the flour, and cook slowly, stirring, until the butter and flour froth together for 2 minutes without coloring. This is now a white roux
2 C milk and 1/4 tsp salt heated to the boil in a small saucepan
A wire whip
Remove roux from heat. As soon as roux has stopped bubbling, pour in all the hot liquid at once. Immediately beat vigorously with wire whip to blend liquid and roux, gathering in all bits of roux from the inside edges of the pan.
Set saucepan over moderately high heat and stir with the wire whip until the sauce comes to the boil. Noil for 1 minute, stirring.
Salt and white pepper
Remove from heat, and beat in salt and pepper to taste. Sauce os now ready for final flavorings or additions.
1-8 Tb Butter – Just before serving the sauce, and after all the final flavorings have been added, remove it from heat. Stir in the butter, a half-tablespoon at a time, beating until each piece of butter has been absorbed into the sauce before adding the next. Spoon the sauce over the hot food, or pour the sauce into a warmed bowl, and serve immediately.
[Recipe Source: Julia Child, Mastering the Art of French Cooking]