Toss the chicken and cornstarch in a large bowl until the chicken is completely coated.

In a medium-sized bowl, whisk the ginger, garlic, brown sugar, soy sauce, oyster sauce, and orange juice until well combined. Set aside.

Shake any excess cornstarch off the chicken. Heat vegetable oil in a large pan over medium-high heat. Add the chicken and fry for 2 to 3 minutes on each side until crispy and golden.

Pour the sauce into the pan and add the dried chilis if using. Stir well until the chicken is coated. Reduce heat to medium-low and simmer for 5 minutes until sauce thickens.

Remove from heat. Garnish with green onions and sesame seeds. Serve warm.