Cook the asparagus in light salted water with lemon juice for 15-18 minutes. Wash and peel the potatoes and cook in salted water for about 20 minutes. Mix 100 ml asparagus water and creme fraiche, bring to the boil.
Bind with some sauce thickener. Stir in butter. Season with salt and pepper. Wash the tomato, remove seeds and dice the flesh. Wash basil, dab dry and, except for something to garnish, pluck the leaves from the stems and cut into strips.
Add the diced tomatoes and basil to the sauce. Spread some oil on the turkey steak, fry for 2-3 minutes on each side and season. Arrange everything together on plates and garnish with basil.