Wash and core the peppers and cut into large pieces. Clean the spring onions, leeks and carrots and cut into slices. Peel, halve and slice the onions. Skin the garlic, cut into slices and roughly chop. Wash the peppers, dry them, cut in half, core and cut the halves crosswise into narrow strips. Brush the potatoes vigorously in warm water, dry them, cut in half lengthways and cut the halves into large cubes.