This light, spicy soup is delicious hot or chilled. The sautéed aromatics turn the broth a rich red-orange, more reminiscent of tomato than watermelon. See if your guests can guess the main ingredient.

Active time: 1 hr Start to finish: 1 hr (3 hr if serving chilled)

Ingredients
For soup
5 cups coarsely chopped seeded watermelon from a 4-lb piece, rind discarded. (we're growing Sugar Baby watermelons this year)
1 fresh lemongrass stalk*
3 tablespoons finely chopped shallot
1 1/2 tablespoons finely chopped peeled fresh ginger
1 tablespoon finely chopped garlic
1 1/2 tablespoons mild olive oil
1 small hot green Thai chile, finely chopped, or to taste (we're growing a firey hot one called "Thai Magic" this year)
2 tablespoons fresh lime juice, or to taste
3/4 teaspoon salt, or to taste

*Available at Asian markets and some supermarkets.  If you can't find fresh lemongrass you can substitute freshly grated  lemon zest.  Avoid the dried lemongrass - I find it pretty tasteless.

For crab
10 oz jumbo lump crabmeat (2 cups), picked over
1/4 cup finely chopped fresh cilantro
1 1/2 tablespoons mild olive oil
1/4 teaspoon salt, or to taste
Accompaniment: lime wedges

Directions
Make soup:
1. Purée watermelon in a blender until smooth and transfer to a bowl. (Don't wash blender.) Discard 1 or 2 outer leaves of lemongrass and trim root end. Thinly slice lower 5 to 6 inches of stalk and then mince, discarding remainder.

2. Cook lemongrass, shallot, ginger, and garlic in oil in a 2-quart heavy saucepan over moderately low heat, stirring, until aromatics are pale golden, about 5 minutes. Add about one third of watermelon purée and simmer over moderate heat, stirring, 5 minutes.

3. Remove watermelon mixture from heat, then transfer to blender along with chile, lime juice, and salt and blend until smooth (use caution when blending hot liquids).

4. Add remaining watermelon purée and blend briefly. Season soup with more chile, lime juice, and salt if desired, blending if necessary. Pour soup through a sieve into a bowl, pressing on and then discarding any solids. Chill soup, uncovered, about 2 hours if serving cold, or reheat in cleaned saucepan.

Prepare crab:
Toss crabmeat with cilantro, oil, and salt.
Divide crab among 4 soup plates, mounding in center, and pour chilled or hot soup around it.

Cooks' notes:
Soup can be made 1 day ahead and chilled. Cover after 2 hours of chilling.
Crabmeat can be picked over 1 day ahead and crab mixture can be prepared 1 hour before serving. Chill, covered.
For a more full-bodied soup, use a coarse sieve or don't strain the puree. Personally, I like it better this way.

Makes 4 first-course servings.

Gourmet
July 2004