Melt butter in a 3-quart saucepan over medium heat; add leeks and cook 5 minutes or until tender-crisp. Add potatoes; cook 5 minutes longer, stirring constantly. Add chicken broth, TABASCO® Green Sauce, and salt; over high heat, heat to boiling. Reduce heat to low; cover and simmer 15 minutes or until potatoes are tender.
In a food processor or blender, puree soup in batches. To serve, garnish each serving with dollop of sour cream or yogurt and top with chives.
Makes 6 servings.