Heat 2 tbsps oil in a non stick pan.
Place the chicken pieces in a glass bowl, add cornstarch, dark soy sauce and mix. Set aside.
Add garlic cloves to the pan and sauté on medium heat till well browned.
Roughly chop spring onion bulbs. Tear spinach leaves and add to the garlic.
Add a little salt and sauté for a while. Transfer into a serving bowl and set aside.
Heat sufficient oil in a wok and deep fry chicken on high heat till golden brown.
Drain on absorbent paper. Heat 2 tbsps oil in a non stick pan, add spring onions and sauté.
Add chicken pieces and mix. Add oyster sauce, salt, crushed red chillies and vinegar and toss.
Crush Sichuan peppers and add to the pan and mix well.
Transfer into the serving bowl over the garlic-spinach mixture and serve hot.