First make the sauce (you can do this some time in advance). Mix all the sauce ingredients, except for the oil and pickles, into a bowl. Heat the oil in a small pan until it is hot, then add the pickles, stir-frying rapidly for 1 minute. Give the sauce mixture in the bowl a good stir and pour it into the pan. Stir until it thickens, then remove and set aside.

Dice the chicken into 1/2 inch cubes and rub with salt and cornstarch. Heat 2 tbl of the oil in a frying pan. When it's very hot, add the chicken and stir-fry quickly for 1 minute. Remove and set aside.

Pour the remaining oil into the pan and bring back to heat. Add the oinion, garlic and spring onion and stir fry together for 1/2 minute. Add the sweet and sour sauce and continue to mix and stir fry together for 10 to 15 seconds.

Return the chicken to the pan and stir fry for 1/2 minute, making sure that all the chicken is coated with the sauce. Serve immediately with steamed rice.