Drizzle potatoes with half of their seasoning, and toss. Roast them on a baking tray lined with parchment for approx 20 to 25 min on 400 degrees F (convect/fan), tossing halfway and adding the remaining half of the potato seasoning halfway.
Meanwhile, cook quinoa according to package directions in water or vegetable broth. Let it to cool on a tray or mixing bowl and stir in juice of 1/2 lemon.
Cook bell peppers and mushrooms on medium heat in their olive oil and seasonings for 6 to 8 min, stirring periodically until browned. Transfer them to a plate. Add chickpeas and their oil and seasonings to the pan, and cook on medium heat for 3 to 4 min.
Serve up all these goods with the dressing, including the tomatoes and olives or use them to top some greens, or even as a side dish. Top optionally with chopped fresh parsley and more lemon juice