Add sugar, garlic and red chili flakes, water, vinegar, salt, ketchup, sambal oelek and fish sauce in a pan and bring it to boil.
Mix cornflour with little water to make a lump free mixture and add it slowly in the pan.
Cook for 3-4 minutes until sauce thickens a bit.
Remove the pan from heat and let it cool.
Transfer in a glass bottle and refrigerate for about a month.
Use as and when required.
If sambal oelek is not available, you can replace it with red chilli paste or add more red chilli flakes instead.You can make this sauce using fresh red chilli peppers as well. If using Jalapeno, remove the seeds and veins if you don't like your sauce too spicy.For a very spicy version, use thai bird's eye chillies.Use a paste of 2-3 chillies in place of sambal oelek if using fresh chillies.