The long, red chillies are generally mild, but they may vary, so as a precautionary measure, when chopping them you may choose to wear disposable gloves.
Remove the stem end of the chillies and then slice them in half lengthways. Chop them finely by hand or use a small food processor but do not reduce them to a paste.
In a small saucepan, place the sugar, 1 cup water, rice wine vinegar, finely chopped garlic and chillies. Over medium heat, bring the mixture to a boil, stirring to dissolve the sugar, then simmer rapidly on medium to high heat for 12 minutes.
Mix the cornflour with the cold water. Lower the heat and re-stir the cornflour and water mixture as the cornflour tends to settle if prepared a little in advance.
Add the cornflour and water to the chillies, stir well and simmer for 3 minutes.
Allow the mixture to cool for a few minutes before bottling. This helps to evenly distribute the chillies through the mixture.
Decant into a sterilised jar or bottle. – See Note 5.When cool, store in the refrigerator for up to three months. When using, remove a portion of sauce from the jar and allow it to come to room temperature. Stir well before serving.