Cut duck breast into 1 inch pieces then season with salt and pepper to taste.
In a large bowl, combine flour, corn starch, soy sauce, minced garlic, soda water and egg. Whisk together then set duck into the marinade and mix well. Rest for 15-20 minutes.
While you’re waiting, chop vegetables and mix together sauce ingredients.
To a large saucepan, add in one tablespoon of neutral cooking oil or butter. Add in chopped onion and bell peppers. Sauté for 2 minutes. Pour in sauce and let simmer while you prepare the duck.
In a separate pan, add in frying oil. You’ll need enough so that the duck is covered, approximately 2-3 inches. Once the oil is hot (about 350 degrees), add in duck and fry for about 3 minutes until golden brown and cooked through. Be careful to not overcook.
Add duck to the sauce and mix well. Serve over a bed of rice (if desired), garnished with green onions and sesame seeds.