Crabmeat, chives, and grated radishes make a colorful floating island in this yellow-corn soup. A dusting of nutmeg contributes to the soup's piquant flavor.
Melt butter in a large saucepan over medium-low heat. Stir in onion and garlic, and season with 1 teaspoon salt and peppercorns. Let cook until onions are soft and translucent, about 10 minutes.
Meanwhile, cut kernels off corncobs with a sharp knife. Set corn aside, reserving cobs.
Add 8 cups water to the onion mixture along with the reserved corncobs. Bring mixture to a boil. Reduce heat, and let simmer until liquid is reduced by almost half and is milky and very flavorful, about 1 hour. Remove corncobs, scraping as much liquid as possible off cobs back into the pan. Discard cobs. Cool corn stock to room temperature.
Meanwhile, bring a large pot of water to a boil. Add reserved corn kernels, and blanch 1 minute. Remove from heat, strain, and run under cold water to stop the cooking.
Set aside 1/3 cup corn kernels for garnish. Combine remaining kernels and cooled corn stock in the bowl of a food processor, working in batches if necessary. Process until smooth. Transfer mixture to a fine sieve set over a bowl. Press down hard on solids to extract liquid; discard solids. Stir in milk to thin soup to desired consistency; transfer liquid to refrigerator. Chill.
Meanwhile, pick over crabmeat, removing any shells or cartilage. Season with lime juice, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Grate radishes using small holes of box grater, and set aside. Snip chives into 1/4-inch pieces with sharp kitchen scissors; set aside.
Adjust seasoning of chilled soup with salt and pepper to taste. Ladle into soup bowls. Place 1/4 cup crabmeat mixture in each. Divide remaining 1/3 cup corn among bowls, and garnish with grated radish and snipped chives. If desired, grate fresh nutmeg and/or sprinkle cayenne over each bowl, and serve.