GRILLED ASPARAGUS PECANS AND BLUE CHEESE DRESSING

60g pecans • 2 tbsp maple syrup • ¼ tsp fine sea salt • 125ml buttermilk • 125ml soured cream • 1 tbsp Worcestershire sauce • ½ x 25g pack chives, finely sliced, plus extra to serve • 100g stilton or other blue cheese • 400g asparagus • 4 little gem lettuces, trimmed and quartered lengthways