3medium leeks (white, light and bright green parts), halved lengthwise, then sliced crosswise 1/4" thick, washed (see note above)
12ouncesyellow potatoes (such as Yukon Gold or Yellow Finn, about 3 lemon-sized potatoes), peeled, in 3/4" chunks
1poundcelery root (1 large), peeled, in 3/4" chunks
6cupssalt-free vegetable stock (preferably homemade, see note above)
1/4 - 1/2cuphalf and half (or milk or heavy cream)
truffle oil (or walnut, porcini, or super-good olive oil), for drizzling
celery leaves, torn (or chervil, parsley or chives), for sprinkling
Melt the butter in a large soup pot or dutch oven. Add the leeks and saute while you prepare the potatoes and celery root. Add the vegetables to the leeks as you work, then give everything a turn to coat it in the butter, and add the stock, bay leaf and salt. Partially cover the pot and bring to a boil, then reduce the heat to maintain a simmer.
Cook for 20 - 30 minutes, until the potato and celery root are soft. Puree the soup smooth with an immersion blender if you've got one, or in a blender, carefully, in batches (don't fill the blender more than halfway full, and hold the lid closed with a thick towel, or cool the soup to room temp first). Add enough half and half to thin the soup to your liking.
Serve the soup hot, with a drizzle of truffle oil and a sprinkle of celery leaves. The soup keeps well in the fridge for up to several days.
You can make a quick stock with the trimmings of the leeks, celery root and potatoes, and 8 cups of water. Throw in a carrot and an onion, in large chunks, if you like, for a bit more flavor. Or use a good quality, prepared vegetable or chicken stock. If you use stock or bouillon with salt, omit the salt in the recipe and add some at the end to taste, instead.To easily wash leeks, cut them as directed below, then place them in a large bowl and fill with cool water. Swish the leeks around to loosen the slices, then let sit for a few minutes. Any sand or silt will settle to the bottom. Lift the leeks out with your fingers, shaking off excess water before adding them to the pot.Nutritional values are based on one of six servings.