1 Add the butter and onion to a heavy-bottomed pan and sweat for 3-4 minutes. Add salt and 500g of chopped asparagus. Cook on a high heat for a further 2-3 minutes with a lid on.
2 Add the chicken stock and keep on a high heat until cooked. Once cooked, blend as quickly as possible to reserve a nice green colour.
3 Bring a pan of water to the boil and add the vinegar and a pinch of salt. Gently whisk the water to create a whirlpool effect, then drop in the eggs and cook for 3-4 minutes for soft yolks. Remove the eggs and place them on kitchen paper to drain.
4 Slice the eight spears of asparagus either lengthways or into chunks.
5 Serve the soup in bowls and garnish with the poached eggs, crème fraîche, olive oil, black pepper and two spears of raw asparagus to each bowl.