Cut chicken breast into bite-sized cubes and toss with cornstarch and salt.
Deep-fry chicken in hot oil until golden brown and crispy; set aside.
In a small pan, simmer garlic paste, soy sauce, sugar, vinegar, and water for 3 minutes until thick and syrupy.
Toss fried chicken cubes into sauce until thoroughly coated.
Garnish with chopped spring onion tops and serve.