Don't mix this bright green soup up with its split pea cousin. Infused with minty flavor and served chilled, it¿s a refreshing way to kick off a meal.
In a large saucepan, bring the broth, peas, salt and pepper to boiling. Reduce heat. Simmer, covered, 7 minutes. Add the 1/4 cup mint and simmer, covered, for 5 to 7 minutes more or until peas are very tender. Remove from heat; cool slightly.
Working in batches if necessary, transfer the soup to a food processor or blender and puree until smooth, adding the 1/2 cup sour cream. (Or puree the soup and sour cream in the pot using an immersion blender.) Strain the soup through a fine-mesh sieve. Refrigerate, covered, for 4 hours or until chilled. Serve in chilled bowls or glasses. If you like, garnish with mint or sour cream.