This is still experimental. I know what I want, but I am still looking for the spicing scheme. It appears that "Chinese" cashew chicken is really a dish created by an American-Chinese in the early 1960s for American palates.
1. Preheat the oven to 350°F.
2. Place the cashews on a baking sheet in a single layer. Reroast in the oven until fragrant, about 5 minutes. Set aside; they will crisp up as they cool.
3. Meanwhile, prepare the sauce: in a small bowl, whisk together the water, cornstarch, hoisin sauce, and soy sauce. Set aside.
4. Brine the chicken pieces for 10 minutes. Rinse, drain and blot with paper towel. (Brine precut breasts for longer, then slice?)
5. In a large nonstick skillet, heat 1 tbsp of the vegetable oil over medium-high heat until very hot. Add half of the chicken to the skillet and stir-fry until translucent, but not brown, about 2 minutes. The objective is to cook the chicken without browning and without drying it out. Transfer to a plate.
6. Add the remaining tbsp vegetable oil to the skillet; then add the remaining chicken, garlic and white parts of the scallions. Stir-fry until the chicken is lightly browned but not cooked through, about 3 minutes. Return the first batch of chicken to the pan. Turn the heat down to medium and add the rice vinegar; cook until evaporated, about 30 seconds.
7. Add the sauce mixture to the chicken; cook, tossing, until the chicken is cooked through and the sauce is nicely thickened, about 1 minute.
8. Remove from the heat. Stir in the scallion greens, cashews and sesame oil.
9. Serve immediately!