Bring two pans of water to the boil. Put 3-4tsp of salt into one and a tablespoon of white wine vinegar into the other. To synchronise cooking the eggs, carefully crack them into cups then pour into the pan of simmering water for a couple of minutes. Cook the asparagus in the salted water at the same time for 3-4 minutes until tender then drain in a colander. Meanwhile simmer the cream and ½ tbsp white wine vinegar in a third pan until it’s reduced by half. Whisk in the butter until it’s all melted then add the prawns and herbs and season with salt and black pepper.
Remove the eggs from the water with a slotted spoon, dry on kitchen paper then put on to warmed plates. Cut the asparagus in half and season then arrange on the plate with the egg, then spoon the sauce and prawns around.