- 
Put the onions and sweet potatoes into a roasting dish. Core and roughly chop the 2 apples and add them to the dish. Sprinkle the crushes seeds over the vegetables and apples and season with salt and pepper. Drizzle 2 T olive oil over the top. Roast for 25 minutes, then turn the vegetables over and roast for a further 25 minutes. The onions should be tender when pierced with a knife. Remove 2 potato chunks and 8 onion quarters and set them aside.
Put half the remaining vegetables into a food processor with half the stock and process to a smooth paste. Transfer to a saucepan. Repeat with the reminaing vegetables and stock. Warm the soup over a gentle heat.
Chop the reserved apple and saute in some olive oil along with the reserved onion and potato until golden. Add to the soup and warm through.
Serve in 4 bowls with a scattering of tarragon leaves.
posted by Mr Falafel