I cooked my first sweet and sour dish in 1984. Pork, of course. The recipe came from Ken Hom’s Encyclopaedia of Chinese Cookery Techniques, a cookery book classic and one I bought the minute it came out that year, on foot of Ken’s successful BBC TV series. I still refer to this book on a regular basis.

Ken’s recipe for the sweet-and-sour sauce goes:

15ml Shaosing wine or dry sherry

15ml light soy sauce

15ml finely chopped garlic

15ml finely chopped fresh ginger root

30ml tomato purée

100ml Chinkiany vinegar – or 60ml cder vinegar

50g sugar or 3 Chinese sugar slabs

225ml chicken stock

15ml cornflour dissolved in 30ml cold chicken stock

15ml sesame oil

The pork cubes are marinated for at least 30 minutes in 15ml light soy sauce, 15ml Shaosing wine or dry sherry, ½ tsp salt and a beaten egg, then drained and blotted dry, dusted with a 50/50 mix of plain flour and cornflour then deep-fried in ground nut oil in a wok for 3 minutes. The oil is drained from the wok then the sweet-and-sour sauce ingredients (minus the cornflour dissolved in stock) are heated to the boil, together with half a pineapple’s worth of chunks. Then the pork is added, together with the cornflour and a teaspoon of sesame oil.

In the text Ken warns about over-thickening, making the sauce too sweet and having it end up a day-glo red hue.

And there you have it. Sweet-and-sour, yin and yang, is all a question of balance.

Since those days, when I followed the recipe implicitly, I’ve experimented. Hallelujah Day One was when I found if I started with a base of fried finely chopped onion, ginger, garlic, tomato purée and a small pinch of five spice I could dispense with the cornflour and get a cleaner flavour, building up the sauce gradually by adding the stock a little at a time (like I do with a bolognaise sauce) Day Two came when I discovered palm sugar – after I developed an interest in cooking Thai food – gave a more subtle sweetness than granulated white.

Since then I’ve done other tweeks including: adding a little or a lot of finely chopped chilli; cooking half a lemon or lime in the sauce – the sweet element has to be adjusted to take account of this; using honey, maple syrup, even pomegranate molasses to get a different flavour/texture; adding a handful of roughly chopped fresh coriander at the last minute. Infinite variety.

Ken Hom’s Encyclopaedia of Chinese Cookery Techniques is no longer in print but if you can find one second hand, buy it.