Cut the chicken breast into bite-sized pieces.
Coarsely blend the garlic and coriander stems.
To marinate the chicken, add the coarsely ground paste, crushed black peppercorns, oyster sauce, fish sauce, light soy sauce, cumin powder, turmeric powder, and sugar. Mix well and keep aside to marinate for 10-15 minutes.
Mix together cornflour and rice flour for dredging in a large bowl. Season it with a teaspoon of salt.
Add in the marinated chicken and mix until the pieces are well coated. Dust off the excess flour.
Heat oil for deep frying. Fry the chicken pieces on medium heat until cooked and golden brown.
The Thai Fried Garlic Chicken is ready to serve. Garnish with fried garlic and chopped coriander leaves. Serve hot with red chili sauce.