Wash the asparagus, cut off the lower, woody ends. Cook the asparagus in boiling salted water for 6-8 minutes. Peel and finely chop the onion. Heat oil in a pan and sauté onion. Add 100 ml water, bring to the boil and stir in the stock. Remove from heat, add vinegar. Season with salt and pepper, let cool down.
Drain asparagus, rinse with cold water and drain. Wash and clean the strawberries, cut a strawberry into slices. Finely dice remaining strawberries. Mix the diced strawberries into the cooled vinaigrette. Arrange the asparagus with the strawberry slices. Spread the vinaigrette over it