Pour oil into a hot wok or skillet. Add chicken and saut until it loses pink color. Break into small pieces. Season with salt and pepper. Mix together chili, lime juice, Nam pla, sugar, shallots and cilantro; pour over noodles and mix thoroughly. Add chicken, shrimp and chilled noodles. Mix well. Serve on a bed of shredded lettuce. Garnish with crisp fried shallots. (To fry shallots, brown in oil until crisp.)