Place the couscous in a large bowl and pour over the hot vegetable stock. Add 2 tablespoons of olive oil, cover and leave to stand for 5 - 7 minutes.
Check the trout for bones. Rub half the lemon zest onto the flesh of the trout on both sides and season.
In a bowl, make up a vinaigrette by mixing the balsamic vinegar, half the lemon juice and the remaining zest.
Fluff up the couscous with a fork and stir in the remaining lemon juice and the chopped herbs.
Place a griddle pan over a high heat and add 2 tablespoons of olive oil. When it is hot, add the trout fillets skin side down and cook for 6 - 7 minutes. Do not turn over.
Remove the trout to plates.
Put the spring onions in the griddle pan with the vinaigrette and fry for 2 - 3 minutes. Pour the spring onions and juices over the trout and serve with the couscous and green salad.
Alternative cooking methodYou can also oven bake the trout at 200°C/400°F/gas mark 6. Wrap the trout in a parcel of lightly greased foil and bake for 15-20 minutes.In a hurry or not all eating together?You can prepare the fish ready for cooking and make the couscous ahead of time so this dish can be ready in minutes.[nutrition-label]