In a small bowl or measuring cup, combine water, fish sauce, soy sauce, sugar and red pepper. Stir until sugar is dissolved and set aside.
Heat 2 Tbs of oil in a large skillet over medium-high heat.
Add onions and garlic and stir fry for about 2 minutes until fragrant. Transfer to a bowl and set aside.
Add remaining oil and heat for about a minute.
Add chicken and cook for about 5 minutes until browned.
Lower to medium heat. Add the reserved sauce and onions to chicken and cook, tossing occasionally, until chicken is cooked through.
Remove from heat and stir in torn basil leaves.
Serve chicken over rice or Asian noodles.
