Oh ... a note on sweet potatoes and yams from Mark, my resident food historian. Sweet potatoes are native to South America and yams to Africa. And, unless you have an amazing market that imports vegetables from Africa, you have probably never seen a yam no matter how many times the supermarket tells you that you have. The confusion of the unrelated Old World and New World tubers probably began when enslaved Africans transferred their word 'yam' (nyami) to the American root. This usage went national in the 1950s when the Louisiana legislature promoted the newly-introduced orange sweet potato under the word 'yam.' It is also interesting that neither yam nor sweet potato is related to white (red-skinned or blue) potatoes. And, just an FYI, a yam is generally 1-2 feet long, and can grow as large as 6 feet.
So, as the weather gets warm in Tucson and remains cold elsewhere, this soup will work all climates!
Sweet Potato Vichyssoise
8 tablespoons butter, divided
4 leeks, white and light green parts only, cleaned and sliced
1 large sweet onion, chopped
1/4 to 1/2 teaspoon cayenne pepper
1 pound sweet potatoes, peeled and thinly sliced
1/2 pound russet potatoes, peeled and thinly sliced
6 cups chicken broth
2 cups water
1 teaspoon salt
freshly ground pepper
1 cup heave cream
1/2 pound fresh crab meat
1/2 teaspoon paprika
Melt 7 tablespoons butter in a large soup kettle. Add leeks and onions and cook over medium-low heat until soft, being careful not to brown them. Add cayenne pepper and stir to incorporate evenly. Add the potatoes, broth and water. Bring to a boil and then reduce to simmer. Cook the soup for 20-25 minutes, or until potatoes are soft. Season with salt and pepper. Purée in a blender in batches and pour into a large bowl through a fine mesh sieve. Stir in cream and chill. (If serving hot, reheat after adding cream.) Before serving, melt remaining tablespoon butter and sauté crab briefly with paprika. Serve soup in shallow bowls with about 1 ounce of crab meat mounted in the center of each plate. Serves 8.