In liquid measure, combine stock, cornstarch and salt; set aside.
In large nonstick skillet, heat half of the oil over medium-high heat; cook chicken, stirring often, for 5 minutes or until no longer pink inside. Transfer to plate.
Reduce heat to medium and add remaining oil; cook garlic, ginger and curry paste, stirring, for 1 minute. Add peppers; cook, stirring, for 2 minutes. Stir stock mixture and pour into skillet; bring to boil. Cook, stirring, for 1 minute or until thickened. Add chicken and onions; cook, stirring, for 2 minutes or until heated through.