Calabaza, Corn, And Coconut Soup

Ingredients

• 2 tablespoons olive oil
• 1 medium onion, coarsely chopped
• 1/4 cup finely chopped fresh cilantro stems
• 2 garlic cloves, coarsely chopped
• 1 (2 1/4-pound) piece calabaza squash or 1 (2 1/2-pound) whole kabocha squash, peeled, seeded, and cut into 1/2-inch pieces (6 cups)
• 4 cups water
• 1 1/4 cups well-stirred canned unsweetened coconut milk (12 ounces)
• 3 ears of corn (fresh or thawed frozen), kernels cut off and reserved for relish (below) and cobs halved crosswise
• 2 teaspoons salt
• 1/4 teaspoon cayenne
• 4 1/2 teaspoons fresh lime juice
• 1/4 teaspoon salt
• pinch of sugar
• 2 tablespoons olive oil
• 2 cups corn kernels
• 2 tablespoons coarsely chopped fresh cilantro
• 1 tablespoon finely chopped shallot