1 quart water thoroughly washed and finely 6 medium-sized boiling potatoes, chopped scrubbed but not peeled 3 slices lean bacon 1½ tsp caraway seeds 2 c milk 1½ tsp salt 1 tsp crumbled dried marjoram 3 medium-sized leeks, including ½ tsp paprika 2 inches of the trimmed green 1/8 tsp ground white pepper tops, cut lengthwise in half, ------------------------------In a heavy 4- to 5-quart casserole, bring the water to a boil over high heat. Add the potatoes, caraway seeds and salt, and cook briskly for about 20 minutes, or until the potatoes show only slight resistance when pierced with the point of a small, sharp knife. With a slotted spoon, transfer the potatoes to a plate, and reserve the cooking liquid. Peel and chop the potatoes fine, stir them into the cooking liquid, add the leeks and bring to a boil over high heat. Reduce the heat to low and simmer the soup partially covered for 30 minutes.
Meanwhile, place the bacon in a heavy 8- to 10-inch ungreased skillet and fry it over moderate heat. Turn the slices with tongs until they are crisp and brown and have rendered all their fat. Then drain the bacon on paper towels, crumble it into bits and set it aside.
Purée the soup through the coarsest blade of a food mill or, with the back of a spoon, rub it through a coarse sieve set over a bowl. Return the soup to the casserole and with a whisk stir in the milk, marjoram, paprika and pepper. Taste and add more salt if necessary. Whisking occasionally, simmer the soup over moderate heat until it is heated through.
Ladle the potato-leek soup into a heated tureen or individual soup plates, sprinkle the bacon bits on top and serve at once. Serves 6 to 8.