Chargrilled garlic & pepper prawns with green chilli dipping sauce

I spent a day at a Thai cooking school in the sunshine coast a year or two back (lovely xmas pressie from my mum) Thought I'd share the this recipe with you guys...........they are gorgeous!

1kg green prawns, deveined
2 coriander roots, cleaned and scraped
12 cloves garlic
1/2 tsp whole white peppercorns
1 tbsp palm sugar (use equiv. splenda)
1 tbsp fish sauce

*Pound white peppercorns, coriander root & garlic to paste
*Dissolve splenda & fish sauce, stir into the paste
*Add prawns, toss and marinate for 2 hours minimum
*Cook prawns 1 min each side on the BBQ (or griddle)

Dipping Sauce
1 tbsp coriander root & stem
2 cloves garlic
5 small green chillies
1/2 cup lime juice
2 tsp palm sugar (use equiv.splenda)
1 tbsp fish sauce

*In mortar, crush coriander, garlic and chillies.
*Add lime juice, splenda and fish sauce