This was easy to scale down to one (actually two, but I like leftovers), from Food & Wine. First you saute about 1/3 pound 1-inch chicken cubes in olive oil until browned, then take them out of the pan and add 1/2 diced onion and 1 leek, sliced thin, reserving some for garnish. (This was the first time I used a leek, and I cut it in half lengthwise, then sliced it thin and put it in a bowl full of water and swished it around with my hands. The leek pieces float to the top and the sediment settles at the bottom of the bowl, so I skimmed the leek off the top of the water and shook it dry, then put it in the pan.) Cook until they start to soften, then add 1 cubed sweet potato and saute another 3 minutes. Then add 1 1/2 cups chicken broth, 1 bay leaf, a pinch or two of sage, salt, pepper and the chicken and simmer until chicken is opaque and potato is soft. Then I mashed some of the potato cubes with a potato masher right in the pot, added 1/2 cup milk and sprinkled with the reserved raw leek slices (these fresh, crunchy leek slices are have a sharp, oniony flavor and contrast with the sweetness of the soup). I love savory sweet potato dishes, and this was good and relatively healthy.