For the chilli jam
For the BBQ sauce and prawns
To make the chilli jam, place the chopped chillies, onion, garlic and water in a food processor and blitz until finely chopped.
Pour the mixture into a medium-sized pot and add the sugar, vinegar, lemon juice and fish sauce. Stir to combine and place over a low heat until the sugar dissolves.
Increase the heat and bring to a boil, then reduce to a gentle simmer. Leave for 35-40 minutes or until the jam gels when tested.
Spoon into sterilised jars, seal and set aside to cool.
For the barbecue sauce, place the tomatoes in a food processor and pulse until chopped.
Place a large pot over a medium-high heat and combine the tomatoes, sugar, vinegar, Worcestershire sauce, garlic, herbs and spices. Bring to a gentle simmer, stirring occasionally, and cook until thickened – about 6-8 minutes.
Whisk in the butter and season to taste.
Preheat the grill to high. Generously brush the prawns with olive oil and cook in batches, flesh side down, for 1-2 minutes.
Toss the prawns into the BBQ sauce, then grill for a further 3 minutes, or until the prawns are just cooked through.
Serve the prawns alongside the chilli jam and lemon wedges and sprinkle with the chopped parsley.