Heat oven to Gas Mark 4, 180°C, fan160°C. Simmer potatoes for 20 minutes, add chickpeas and bring to the boil. Drain and keep warm until needed.
Wash beetroot, cut off top and tail, chop into wedges. Roughly chop courgettes into 2.5cm (1in) chunks and cut peppers into strips. Place in a roasting pan, add oil and toss.
Roast for 20 minutes, add the tomatoes and cook for a further 10 minutes. Mix together crème fraîche and chopped coriander. Place rocket, potatoes, chickpeas and roasted veg on a plate, sprinkle with seeds. Serve dressing in small bowl.