Chicken and Broccoli Stir-Fry

In a medium bowl, toss the chicken with 1 teaspoon of the cornstarch, 1 teaspoon of the salt, soy sauce, sugar, sherry, sesame oil, scallion whites, half the garlic and half the ginger. Marinate at room temperature for 15 minutes. Mix the remaining cornstarch with 0.33 cups water. Heat a large nonstick skillet over high heat. Add 1 tablespoon of the oil and heat. Add the broccoli stems, and stir-fry for 30 seconds. Add the florets and the remaining garlic, ginger, 2 tablespoons of water, and season with ¼ teaspoon salt. Stir-fry until the broccoli is bright green but still crisp, about 2 minutes. Transfer to a plate. Get the skillet hot again, and heat 2 tablespoons oil. Add the chicken. Stir-fry until the chicken loses its raw color and gets a little brown, about 3 minutes. Add the hoisin sauce, return the broccoli to the pan and toss to heat through. Stir in the reserved cornstarch mixture and bring to a boil to thicken. Serve with rice.