Preheat oven to 220°C (200°C fan-forced) and line a large tray with baking paper. Combine oil and Old Bay Seasoning to create a marinade for the tray bake.
Place prepared vegetables in a large bowl with the marinade and toss ingredients until well coated all over.
Lay vegetables flat on prepared tray and place in the oven. Bake for 40-45 minutes or until vegetables are tender and browned. Toss halfway through cooking.
Meanwhile, combine chickpeas with oil and Old Bay, ensuring to coat well, and set aside.
Once vegetables are ready, remove tray from oven and change oven to Grill mode on HIGH heat. Scatter chickpeas over vegetables and place haloumi slices on top.
Return tray to oven under grill and cook for another 6-8 minutes or until haloumi is lightly charred.
Place all ingredients for the Salsa Verde Dressing in a small food processor and blend until smooth.
Prepare couscous. In a large heatproof bowl, add dry couscous and water. Stir to combine, cover, and allow to stand for 5 minutes. Remove cover and fluff with a fork to separate grains. Add Salsa Verde Dressing and stir through to coat couscous.
Once ready, remove tray bake from oven and spoon Dressing over top before serving. Enjoy with fluffy couscous!