Begin by slicing your boneless, skinless chicken breast into thin strips. In a mixing bowl, combine the chicken with soy sauce and cornstarch, ensuring every piece is well-coated. Cover and let the chicken marinate for 10-15 minutes at room temperature.

While the chicken is marinating, heat 2 tablespoons of vegetable oil in a large skillet or wok over medium-high heat. Once the oil shimmers, add minced garlic and freshly grated ginger. Sauté for about 30 seconds, stirring continuously until aromatic.

Add broccoli florets to the hot skillet, stir-frying for 3-4 minutes until they become bright green and tender-crisp. Remove from pan to retain color and crunch.

In the same skillet, add another tablespoon of vegetable oil if needed. Increase heat to high and add the marinated chicken in a single layer. Cook for 5-7 minutes, stirring occasionally, until golden brown and cooked through.

Return the cooked broccoli to the skillet with the chicken. Pour in oyster sauce and mix gently. Cook for another minute to heat through and meld flavors. Transfer to a serving dish.