In a saucepan, bring stock, garlic, curry powder, salt and pepper to the boil. Stir in peas and celery. Return to the boil. Reduce heat to medium low; cover and simmer for 6 to 8 minutes or until peas and celery are tender. Cool slightly.
Place pea mixture, mint and milk in a blender or food processor; cover and process until smooth. Return to saucepan over medium heat. Stir in cream; heat through (do not boil). Stir in lemon juice. Garnish with fresh mint if desired.