Marinate the chicken while you prepare the rest of the ingredients
1 pound chicken breast (about 2 breasts), cubed
3 scallions, whites only, thinly sliced on an angle
2 cloves garlic, minced
1-inch piece peeled fresh ginger, minced
1 tablespoon soy sauce
2 tablespoons sugar
1 tablespoon, plus 1 teaspoon cornstarch
1 1/4 teaspoons salt
1 tablespoon dry sherry (I omitted b/c did not have)
1 tablespoon dark sesame oil
About 1/3 cup water
3 tablespoons vegetable oil
5 to 6 cups broccoli florets
3/4 to 1 teaspoon red chili flakes, optional
1 tablespoon hoisin sauce
Garnish: toasted sesame seeds, optional
Serving suggestion: Jasmine rice
In a medium bowl, toss the chicken with the scallion whites, about half the garlic and ginger, the soy sauce, sugar, 1 teaspoon of the cornstarch, 1 teaspoon of the salt, the sherry, and the sesame oil. Marinate at room temperature for 15 minutes. Mix the remaining cornstarch with 1/3 cup water.
Heat a large nonstick skillet over high heat. Add 1 tablespoon of the oil and heat. Add the broccoli and stir-fry for 30 seconds. Then add the remaining garlic, ginger, 2 tablespoons of water, and season with 1/4 teaspoon salt, and pepper. Stir-fry until the broccoli is bright green but still crisp, about 2 minutes. Transfer to a plate.
Get the skillet good and hot again, and then heat 2 more tablespoons oil. Add the chicken and chili flakes if using. Stir-fry until the chicken loses its raw color and gets browned, about 3-4 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. Add more water if need to thin the sauce, if necessary. Taste and season with salt and pepper, if you like. Mound the stir-fry on a serving platter or divide among 4 plates and garnish with sesame seeds; serve with rice.