Ingredients  
250g cooked king crab legs (also called prime sections)
120ml white wine 
50ml white wine vinegar
½ tbsp shallots 
225g diced butter

Method 
Cut the crab legs into half on the long side so you have half drainpipes.  

Fill the thermos with boiling water.  

Bring the wine, vinegar and shallots to the boil and reduce until you have only 1 tbsp of liquid remaining. Strain and return to the heat. Add the butter one cube at a time whisking constantly until you have only 2 pieces left. The sauce should be thick and glossy. Add the remaining 2 cubes of butter off the heat. Empty the flask and put the sauce into the flask to keep warm while you cook the crab.

The crab comes cooked usually so you can serve it cold but I like it warm with a little golden char as it gives a lovely contrasting texture. To do this you can either cook over hot coals on your braai or bbq or cook under a hot grill. Serve with the sauce in a dipping bowl.