Place the cubed chicken in a bowl with the garlic, ginger, dry sherry, and cornstarch. Mix well and marinate for 30 minutes.
While the chicken is marinating, prepare the sauce by combining orange juice, dark soy sauce, sesame oil, brown sugar, and chili paste in a small bowl. Whisk until smooth.
When the chicken is nearly ready, heat the wok over high heat and add a bit of oil.
Add the marinated garlic and ginger to the wok and stir-fry until aromatic, about 30 seconds.
Add the marinated chicken and stir-fry until it changes color and is nearly cooked through, about 3-4 minutes.
Push the chicken up to the sides of the wok, making a well in the middle.
Pour the prepared sauce into the well in the center of the wok.
Mix the sauce and chicken together, tossing to coat evenly.
Stir-fry for another minute until the sauce is glossy and the chicken is fully cooked. Serve hot.