Peel the asparagus only on the lower half, cut off any woody end, then cut into 3 cm long pieces. Boil salted water with sugar, lemon juice and butter, put in the asparagus and cook for about 10 minutes.
For the salad dressing, mix the vinegar and oil together, season to taste, season with salt and pepper if necessary, pour over the warm asparagus, leave to steep for approx. 15 minutes. Then add the halved strawberries, mix and serve immediately.