Combine the chicken, oyster sauce, palm sugar, garlic, ginger, Thai chiles and 1 Tablespoon of the oil in a large bowl. Set aside to marinate for 30 minutes.
Heat the remaining oil in a large skillet or wok, add the onions, and cook, stirring frequently, until the onion begins to soften. Add the chicken and all of the marinade and cook, stirring frequently, until the outside of the chicken is no longer pink (it shouldn't be cooked through at this point).
Add the Chinese broccoli, tamarind pulp and fish sauce and continue to cook until the chicken is cooked through and the Chinese broccoli leaves have wilted and the stems are tender crisp. Add the Thai basil and the toasted cashews.
Continue to cook for another minute or so, until the Thai basil has just begun to wilt. Serve immediately.
Gluten FREE!