Tip the couscous into an ovenproof dish. Stir the salt into the measurement water and pour over the couscous. Stir once to make sure all the grains are submerged in the water, then cover with a clean tea towel and leave to stand for about 10 minutes. Using your fingers, rub the oil into the grains until light, airy and any lumps are broken up. Scatter over the butter and cover with a piece of damp greaseproof paper. Place in a preheated oven, 180°C (350°F), Gas Mark 4, for about 10–15 minutes until heated through.
Meanwhile, bring the stock and saffron to the boil in a heavy-based saucepan. Drop in the broad beans, artichoke bottoms, courgettes and garlic and cook for 2–3 minutes. Add the peas and spring onions, reduce the heat and simmer for 10 minutes until the vegetables are tender. Season and stir in the dill.
Pile the couscous on a shallow serving dish. Using a slotted spoon, remove the vegetables from the broth and arrange over the couscous. Drizzle with a little broth and serve the remaining broth separately in a jug.