Rinse the barley and cook in a medium size pot with boiling water. Simmer for 20-25 minutes until it softens but still has a little bite. Drain and leave to cool.
Wash the parsley, coriander and mint and dry thoroughly. With some scissors cut the leaves and discharge the stalks. Set aside.
Wash the grapes and cut in half.
Assemble the salad by mixing all the ingredients together.
In a small bowl add six table spoons of olive oil, the juice of the lemon and season with salt and pepper. Add the dressing and mix gently to coat just before serving.