Steam the couscous per the package directions (i recommend using a stock and steaming twice for 20 minutes each, draining and raking the pearls each time and adding a dash of oil. Then steam again for about 10 minutes to finish the cooking process. Drain and add splash of stock and oil and give them a final rake through to be sure they do not stick together. Set aside in a covered bowl.
Prep and chop all the vegetables into bite size pieces for the roasting process; roast vegetables together in combinations based on their required cooking time (for example; root vegetables on one tray and softer vegetables such as zucchini, onion and mushrooms on separate tray.)
Season all the vegetables with salt and pepper to taste, garlic cloves and drizzles of oil. Roast each tray until the vegetables are tender enough for a fork to go right through the pieces. Remove from oven and let cool for about 5 minutes.
Please the cooked couscous in a large deep bowl and mix in all the roasted vegetables in small batches; blending carefully as you go. Add some stock and drizzles of oil as needed to keep the mixture well blended. Chop the fresh parsley leaves and scatter along the top of the mixture and serve immediately at room temperature.
You can make this dish ahead of time, as I believe the flavors become more pronounced as they rest overnight. Remove from the fridge about 15 to 20 minutes before serving or you can reheat the mixture to remove the chill as well.