First, take out two eggs (one as backup) and the jar of mustard from the refrigerator to bring them to room temperature. Finely slice the white and red onions, then sprinkle with a little salt to draw out excess moisture. Peel the asparagus to remove the tough outer layer.

Steam the asparagus for about 25 minutes. For the mayonnaise: separate one egg yolk (save the white for breakfast), add a little mustard and salt, and whisk together. Gradually add sunflower oil, a few drops at a time, whisking until the mixture thickens. Add a splash of raspberry vinegar or red wine vinegar to taste.