In a small bowl, combine diced chicken, salt, cornstarch, and soy sauce. Mix thoroughly and let sit a few minutes.
Meanwhile, dry-roast the peanuts. Heat wok or skillet to med high heat and add peanuts, tossing occasionally till peanuts begin to “pop.” Reduce heat to med/low, and continue to roast 3-4 more minutes. These peanuts can be crushed or added whole to the stir-fry later.
Heat cooking oil in wok or skillet over med/ high heat till oil begins to ripple or shimmer. Add chicken and stir-fry 2-3 minutes, then remove chicken only using slotted spoon so oil stays in wok.
Add carrots and lettuce root (or celery) and stir-fry 1-2 minutes till just beginning to turn tender-crisp. Return chicken to pot and add peanuts (crushed or whole), oyster sauce, sugar, sesame oil, and hot pepper paste, if you want the dish to be spicy. Add a little water to thin sauce if desired. Stir to mix, then allow sauce to come to a boil.
Serve over rice.
