Wash and roughly chop tomatoes and place in a large saucepan.
Wash, deseed and roughly chop red peppers and add to tomatoes.
Roughly chop the chilies and add to the pan. Keep the seeds if you want your sauce extra hot.
Peel and roughly chop the garlic, onions, and ginger then add them to the pan.
Finely chop the lemongrass and lime leaves, and add them to the pan along with the star anise, sugar, and fish sauce.
Place the pan over medium heat, cover it with a lid and bring the mixture to a boil.
Lower the heat and gently simmer for an hour with the lid on.
Remove the lid and simmer for another hour or until the mixture is almost dry.
Take the pan off the heat, remove the star anises and place the mixture in a food processor.
Blitz until nice and smooth and store in a jar. Keep in the fridge for up to 3 months.