Wash the potatoes and cook in boiling water for 15-20 minutes. Wash the green asparagus and cut off the woody ends. Peel the white asparagus, cut off the woody ends and wash the asparagus. Cook white asparagus in boiling salted water for about 20 minutes, green asparagus for about 10 minutes. Drain potatoes, rinse with cold water, peel and halve. Heat oil in a pan and fry potatoes until golden brown. Season with salt.
Remove the asparagus and keep warm. Measure 1/8 litre asparagus stock and put it into a pot. Add sauce powder and lemon juice and mix. Bring to the boil while stirring. Add butter in pieces and melt in it at low heat. Arrange asparagus, sauce, roast potatoes and salmon on a plate and serve garnished with chervil, dill and lime slices as desired