Cut chicken into 1.5-inch pieces. In a medium bowl, combine chicken with soy sauce, oyster sauce, honey, cornstarch, and black pepper. Mix well to coat. Let sit for at least 5 minutes while you prep the onion and garlic.

Heat 2 tablespoons oil in a large skillet over medium-high heat until shimmering. Add marinated chicken in a single layer and cook undisturbed for 3-4 minutes until golden. Flip and cook another 3 minutes until mostly cooked through.

Push chicken to the edges of the pan. Add sliced red onion and chopped garlic to the center. Sauté for 2-3 minutes, stirring frequently, until onion softens and garlic becomes fragrant and golden.

Increase heat to high. Add lemon juice, lemon zest, and chopped cilantro. Toss everything together for 1 minute to glaze the chicken and combine flavors.

Serve immediately over rice or with your favorite side dish.