Start by cutting the chicken breasts into bite-sized pieces. Season with the pepper and salt, ensuring every piece is well-coated.
In a wok or large skillet, heat the oil over medium-high heat. Make sure the oil is hot enough before adding the chicken to achieve a nice sear.
Add the seasoned chicken to the hot oil. Stir-fry for about 5-7 minutes or until the chicken is cooked through and golden brown. Remove the chicken from the skillet and set it aside.
In the same wok, add a little more oil if needed, and toss in the garlic and ginger. Stir-fry for about 30 seconds until fragrant, being careful not to let them burn.
Add the celery, carrot, broccoli, red bell pepper, and leek to the wok. Stir-fry for 3-5 minutes, allowing the vegetables to become tender yet retain their crunch.
Return the cooked chicken to the wok along with the baby corn and green peas. Toss everything together to mix well.
In a small bowl, mix the soy sauce, sugar, and corn starch. Pour this mixture over the chicken and vegetables in the wok. Stir everything together until the sauce thickens and everything is evenly coated.
If you're using pak choi, add it in the last minute of cooking to ensure it remains crisp. Stir well to combine, and cook for an additional minute.
Once everything is cooked to perfection, serve your Chicken Chopsuey Dominican-Style hot over a bed of rice or noodles. Enjoy!