For the dressing: In a small bowl add all ingredients and mix well. Set aside for about 1/2 hour to allow the flavors to develop. Taste and adjust seasoning before serving.
For the salad: Combine papaya, bean sprouts, cucumber, onion, and red chile in a large bowl. Pour over the dressing and mix well. Mound onto a platter, garnish with cilantro leaves, and surround with butter lettuce leaves.