Trim the ends of the asparagus and, using a vegetable peeler, peel the bottom halves. In a large, deep skillet, bring a few inches of salted water to a boil. Add the asparagus and cook until al dente, about 5 minutes. Drain and rinse under cold water.
In a small bowl, whisk together the vinegar and mustard. Drizzle in the olive oil, whisking until combined; season to taste with salt and pepper.
Place the asparagus on a platter and drizzle with the dressing. Halve the hard-boiled egg and press through a sieve over the asparagus.