Wash the potatoes. Cook in boiling salted water for about 20 minutes. In the meantime, wash the asparagus and cut off the woody ends. Cut asparagus into bite-sized pieces. Cook in little boiling salted water for about 10 minutes. Then drain and collect the asparagus water. Rinse potatoes cold, peel and slice.
For the aioli, peel the garlic and press it through the garlic press. Peel and finely chop the onions. Mix with mayonnaise, crème fraîche and 5-7 tablespoons asparagus water. Season to taste with salt, pepper and lemon juice. Mix potato, asparagus, shrimps and aioli. Cover and let stand for at least 30 minutes. Season again and serve garnished with lemon and dill