Cut the melon into pieces, leaving something aside for garnishing. Peel melon. Peel and chop the onion. Finely mash melon and onion with nectar and toast. Season to taste with vinegar, salt and pepper.
Wash and clean the cucumber, celery and paprika and, except for the celery green for garnishing, dice finely and add to the soup. Cover and chill for at least 1 hour.
Wash the herbs, shake dry and put some mint aside for garnishing. Finely chop the remaining herbs. Stir into the soup just before serving. Serve the soup and garnish with melon and mint.