Julia's Basic Leek and Potato Soup

from Cooking at Home

INGREDIENTS

2	tb butter
3	cups sliced leeks, white and palest green, trimmed and rinsed well. [about 12 oz before cleaning up]
1 1/2	cups sliced onions (about 6 oz or 2 medium onions)
2	tbs flour
6	cups water (*susan* uses homemade stock very often)
4	cups peeled, diced potatoes, cut into 2-inch chunks, about 1.5 lbs (russets or yukon)
1.5	tsp salt, or to taste
1/2	tsp freshly ground white pepper
garnishes as wanted
	chervil fronds
	chopped chives
	creme fraiche
	heavy cream

INSTRUCTIONS

1.	Melt the butter in a saucepan over moderate heat. Stir in the leek and onion pieces to coat with butter, cover the pan, and reduce the heat. Cook slowly, stirring occasionally, for 10-15 minutes,until the vegetables are very soft but not colored.
2.	Uncover, sprinkle on the flour, stir to distribute it well, and cook for 2 minutes over moderate heat. Remove from the heat and let cool for a moment.
3.	Then, stirring continually, gradually pour in 1 1/2 cups of the water and bring to the simmer. When the liquid is smooth and starts to thicken, stir in the rest of the water, then add the potatoes and season with salt and pepper.
4.	Quickly heat the soup to a gentle boil, cover the pan, and lower the heat. Simmer for about 20 minutes, until the potatoes are tender. Correct seasonings.
5.	To serve, mash, blend, or puree through a food mill to the desired consistency.