In a small bowl, whisk the cornstarch into the chicken stock. Stir in the oyster sauce, sherry, and sugar, then set it aside.
Lightly toast the cashews in a dry skillet over low heat, tossing them occasionally, until the nuts are warm and fragrant, about 5 minutes.
Heat a large nonstick skillet over medium-high heat. Add the oil, swirling it to coat the pan. Add the scallion whites and ginger, stir-frying until they are just fragrant, about 30 seconds. Add the broccoli, cook it for 2 minutes, then add the garlic and crushed red pepper (if using), tossing them to mix them well. Pour in the water and cover the pan immediately. Reduce the heat to medium. Steam until the broccoli is just crisp-tender, about 3 minutes.
Uncover the skillet and raise the heat to medium-high. Add the bell peppers, tossing to combine them with the mixture. Stir in the sauce made in Step 1, heat it until it's bubbling, then add the scallion greens and cashews. Serves 4.
Per serving (1 cup): Calories 172 ● Total Fat 10 g (15% DV) ● Saturated Fat 2 g (9% DV) ● Cholesterol 0 mg ● Sodium 560 mg (23% DV) ● Total Carbohydrate 16 g (5% DV) ● Fiber 3 g (12% DV) ● Sugars 7 g ● Protein 5 g (10% DV) ● Vitamin A (23% DV) ● Vitamin C (114% DV)
Percent daily values are based on a 2,000-calorie diet. Your daily values may be higher or lower depending on your calorie needs.