Preheat the oven to 200°C/gas mark 6. Put the onions, peppers, courgettes and fennel in a large roasting tray and drizzle over the olive oil. Sprinkle over the sumac and then stir the vegetables well until they are evenly coated.
Place in the oven and roast for 25 minutes. Add the radishes and tomatoes, then roast for 10-15 minutes until golden and tender. Remove from the oven and leave to return to room temperature.
Meanwhile, put the couscous in a heatproof bowl and pour over the hot stock. Cover with a plate and leave for around 10 minutes, until all the stock has been absorbed. Remove the plate and fluff the grains with a fork. Leave to cool, then season with black pepper and stir through the dill. Serve the couscous with the roasted veg on top.
For more herbs and spices, click here