Step 1

In a medium bowl, whisk together 2 tablespoons of the chicken broth, 1 tablespoon of the vegetable oil, 1 tablespoon of the oyster sauce, 1 tablespoon of the cornstarch, ¼ teaspoon salt, and ¼ teaspoon pepper. Add the chicken and toss to coat. Cover and let sit for 15 minutes.

Step 2

Meanwhile, fill a large bowl with ice water. In a large skillet, bring 2 quarts salted water to a boil over medium-high heat. Add the broccoli and cook until bright green and just tender, about 2 minutes. Use a slotted spoon to remove the broccoli to the ice water to stop the cooking. Drain and pat dry. Empty and dry the skillet.

Step 3

In a large liquid measuring cup, whisk together the soy sauce, sherry, brown sugar, sesame oil, and the remaining ⅓ cup chicken broth, 2 tablespoons oyster sauce, and ¼ teaspoon pepper. Place the remaining 1 tablespoon cornstarch in a medium bowl and add 2 tablespoons of the soy sauce mixture, whisking well to form a slurry.

Step 4

In the same skillet, heat the remaining 2 tablespoons vegetable oil over medium-high heat. Add the chicken in a single layer to the hot pan and allow to cook undisturbed until brown on one side, 1 to 2 minutes. Flip and cook for another 30 seconds before removing the chicken to a plate. Add the ginger, garlic, and green onion whites. Cook, stirring constantly, until fragrant, 30 seconds. Stir in the soy sauce mixture and bring to a simmer. Add the chicken and broccoli to the skillet. Stir in 2 tablespoons of the slurry mixture and simmer until the sauce is glossy and thick enough to coat the back of a spoon, about 2 minutes, adding more slurry, 1 teaspoon at a time, if the sauce is too thin.

Step 5

Sprinkle with the green onion greens. Serve over steamed rice.