Lobster Salad Canapes

Name: Lobster Salad Canapes
Ingredients: 1 (1 1/2-pound) live lobster; 2 thick seedless cucumbers (usually plastic-wrapped; at least 1 3/4 inches in diameter), cut into 36 (1/4-inch-thick) slices; 2 tablespoons mayonnaise; 2 to 3 teaspoons fresh lime juice; 1 1/2 teaspoons minced fresh jalapeño chile (including seeds); 1/4 teaspoon salt; 1/3 cup finely diced peeled mango; 1/4 cup finely chopped celery; 2 tablespoons finely chopped red onion; 2 tablespoons finely chopped fresh cilantro; Garnish: thinly sliced fresh cilantro; a 1 1/2-inch scalloped round cookie cutter (optional)