Slice the chicken into 1 ½ to 2-inch pieces, about ¼ inch thick, making sure to cut against the grain. Add the water and soy sauce to the chicken in a medium bowl and mix to coat well; set aside for 5 minutes for the chicken to absorb the liquid. Add the arrowroot and vegetable oil and mix until well incorporated and the chicken is coated. For the best results, set the chicken aside for 15 to 20 minutes to marinate. (This is a good time to prep the rest of the ingredients.)
Zest and juice the oranges so you have 1 tablespoon of zest and 1/2 cup of juice. Combine the orange juice, zest, soy sauce, honey, ginger, garlic, and crushed red pepper in a saucepan and cook over medium heat to meld flavors, about 5 minutes.Reduce heat to low and barely simmering. Add the arrowroot to 2 tablespoons of water, then whisk into the sauce over low heat (add another teaspoon of arrowroot if needed to thicken). Taste to adjust for sweetness or saltiness. Remove from heat and set aside.
Heat 2 tablespoons oil in a large skillet over medium-high heat. Add the vegetables and cook until just tender, about 5 minutes. Remove from the skillet and heat another tablespoon of oil over medium-high heat.
Add the chicken to the skillet and cook until browned and tender, about 5 minutes.
Reduce heat to low and add the cooked vegetables and sauce to the chicken, stirring so the sauce coats everything. Remove from heat and sprinkle with cashews just before serving.
Notes
TIPS & VARIATIONS:
Slightly freeze the raw chicken until firm but not frozen for easier slicing.
Serve over rice or in lettuce cups.
Substitute roasted and salted pistachios for cashews.
MAKE AND FREEZE: To make and freeze as part of a meal-prep day, make the sauce and stir-fry the chicken, but skip cooking the vegetables (the vegetables will taste best when made fresh) and reserve the cashews. Freeze the chicken in the sauce. To finish the meal, stir-fry the vegetables and reheat the sauce and chicken. Add the vegetables to the chicken and garnish with fresh cashews.