Heat the oil in a large pan over medium high heat.
Place the chicken in the pan in a single layer. Season with salt and pepper. You may need to cook the chicken in batches.
Cook the chicken for 4-6 minutes or until browned and cooked through. Repeat the process with any remaining chicken.
Add the peppers to the pan with the chicken and cook for 3-4 minutes or until softened.
Add the garlic and ginger to the pan and cook for 1 minute.
In a small bowl, whisk together the chicken broth, sugar, soy sauce, rice vinegar and cornstarch.
Pour the chicken broth mixture over the chicken and vegetables and bring to a simmer.
Cook for 1-2 minutes or until sauce has just thickened.
Stir in the mango chunks and serve.