Add water into grated garlic and ginger with 1 tbsp water each. After 15 minutes, strain and press all the garlic and ginger juice, we only use the juice for this recipe. You can use garlic & ginger scrap for another dish.
In a bowl, combine all the ingredients except cornstarch and stir until the palm sugar is dissolved.
In a big bowl, combine boneless chicken thigh with cornstarch, salt, white pepper, and 10 tbsp teriyaki sauce mixture, mix thoroughly. Marinate for 30 minutes.
Heat 1 tbsp cooking oil in a pan over medium-high heat. Cook boneless chicken thigh, don't overcrowed. When the chicken is golden brown, flip and add 3 tbsp water and cook until the water absorbs into the chicken. Do the same with the rest of the chicken.
Transfer the remaining teriyaki sauce mixture into a saucepan. Heat over low-medium heat.
Combine cornstarch with water and add it into a saucepan. Keep stirring and cook until the sauce is thickened.
Transfer the chicken into a cutting board, then cut into a bite-sized.
Serve on a plate with warm rice and drizzle with some teriyaki sauce.
Enjoy!