1 fresh lemongrass stalk, root end trimmed and 1 or 2 outer layers discarded
1 large onion, chopped
2 tablespoons unsalted butter
2 tablespoons olive oil
1 3/4 lb pumpkin, kabocha or butternut squash, peeled, seeded, and cut into 1-inch pieces (4 cups)
2 1/2 cups fresh corn kernels
5 cups water
1 large onion, chopped
2 tablespoons unsalted butter
2 tablespoons olive oil
1 3/4 lb pumpkin, kabocha or butternut squash, peeled, seeded, and cut into 1-inch pieces (4 cups)
2 1/2 cups fresh corn kernels
5 cups water
Cut off and discard top of lemongrass, leaving a 6-inch stalk, then smash stalk with side of a large heavy knife.
Cook lemongrass, onion, and 1 teaspoon salt in butter and oil in a heavy medium pot over medium-low heat, stirring occasionally, until onion is softened, about 10 minutes. Add squash or pumpkin, corn, water, 1 1/2 teaspoons salt, and 1/2 teaspoon pepper and bring to a boil over high heat.
Reduce heat and simmer, covered, stirring occasionally, until squash is tender, about 10 minutes. Remove from heat and discard lemongrass.
Purée soup in 3 or 4 batches in a blender until very smooth (use caution when blending hot liquids), straining each batch as blended through a fine-mesh sieve into a large heatproof bowl, pressing hard on and then discarding solids. Season with salt and pepper and reheat if necessary.