Cracked Wheat, Green Olive and Lemon Tabbouleh

1¼ cups fine burghul or cracked wheat
2 cups boiling chicken stock or water
3 spring onions, finely chopped
1 small handful each flat-leaf parsley, mint and coriander, finely chopped
2 handfuls of rocket or spinach leaves, thinly shredded
½ cup roughly chopped green olives
¼ cup olive oil
finely grated zest and juice 2 lemons
2 cloves garlic, crushed
sea salt and freshly ground pepper
¼ cup roughly chopped pistachio nuts