Preheat oven to 400 ° C. Toss the squash, onion and mushrooms in a bowl, add 2 tbsp of oil, sugar, salt and pepper. Mix well. Spread on a parchment plate. Bake 30 min or until complete evaporation of the water until a slight coloration. Book in large bowl.
Heat to boiling 1 cup mushroom broth and add the couscous. Cover and let stand 5 min. Separate the couscous grains with a fork. Add c. in s. butter if desired. Combine couscous with grilled vegetables. Add the citrus juice, oil, parsley and adjust the seasoning. Serve warm or cold dish. Keeps for 4 days.