Husk the corn and cut the kernels from the cobs to yield 5 cups. Set aside 3 cobs and discard the rest.
In a 4-quart saucepan, melt 4 Tbs. of the butter over medium heat. Add the thinly sliced shallot and cook, stirring occasionally, until tender but not browned, about 5 minutes. Set aside 1/2 cup of the corn kernels (cover and refrigerate), and add the rest to the pan. Add the milk, 1-1/2 cups water, 2 tsp. salt, and 1/4 tsp. pepper. Bring to a gentle simmer.
Holding a cob over the pot, scrape it with the dull side of a knife to release some of the corn milk. Add the cob to the pot, breaking it in half to fit, if necessary. Repeat with the remaining cobs. Simmer, stirring occasionally, until the corn kernels are just tender, 8 to 12 minutes.
Discard the corn cobs, and purée the soup in batches using a blender or food processor. Pass through a fine-mesh strainer, pressing hard on the solids with a ladle to extract as much liquid as possible. Refrigerate the soup until cold. When ready to serve, remove the soup from the refrigerator to take off some of the chill. (You want it cool, but the flavors will be muted if it’s too cold.)
Heat the remaining 1 tsp. butter in a small skillet over medium-low heat. Add the chopped shallot, and cook, stirring, until tender, about 3 minutes. Add the reserved 1/2 cup corn, and cook, stirring occasionally, until tender, 1 to 2 minutes. Let cool completely.
In a medium bowl, combine the corn, crab, chives, 1 Tbs. of the lemon juice, the olive oil, 1/2 tsp. salt, and a few grinds of pepper. Toss gently to combine. Season to taste with more salt, pepper, and lemon juice.
Add the remaining 1 Tbs. lemon juice to the soup, and season to taste with salt and pepper. Divide among bowls, garnish with a spoonful of the crab and corn mixture, and serve.
Make Ahead Tips
The soup may be prepared up to 2 days ahead and refrigerated, covered. Make the crab salad and top the soup just before serving.
nutrition information (per serving):
310, Fat Calories
16, Saturated Fat
8, Polyunsaturated Fat
1.5, Monounsaturated Fat
Photo: Scott Phillips