Preheat a barbecue or grill to it's highest setting.
Pour the vegetable stock into a saucepan and bring to the boil.
Heat 1 teaspoon oil in a frying pan over a medium heat and toast the couscous for a couple of minutes. Tip into a large bowl and add the hot vegetable stock. Cover with cling film and allow to stand for 5–10 minutes.
Bring a large saucepan of salted water to the boil and blanch the broccoli, peas and broad beans for a couple of minutes and refresh in ice-cold water.
Remove the broccoli from the water, drain and toss in a bowl with the spring onions and 1 teaspoon oil. Place onto the barbeque or under the grill and char on all sides. Remove from the grill and set aside until ready to serve.
To make the dressing, place all the ingredients in a medium glass bowl and mix well.
Scatter the leaves onto a serving platter and dress with the couscous, broccoli, peas, broad beans, spring onions and herbs. Top with the dressing and serve.