Chinese sweet and sour sauce (Tangcu jiang)

1. Mix the rice vinegar, sugar, ketchup, soy sauce and salt in a small pan.

2. Pour in most of the water and bring to the boil over medium heat, stirring, until the sugar has completely dissolved.

3. Mix the cornflour with the remaining cold water until smooth.

4. Pour the cornflour mixture into the boiling sauce in a thin stream, stirring constantly.

5. Cook for 1-2 minutes until the sauce thickens and becomes glossy and translucent.

6. Taste and adjust the balance with a little vinegar or sugar, and serve warm or cooled.

Tip: A basic sauce for battered meats, spring rolls, prawn toast or wok-fried vegetables. For a fruitier version, replace half the water with pineapple juice; it keeps for a week in the fridge.