Bring a large pot of salted water to a boil. Add the asparagus pieces and blanch for about 2-3 minutes until bright green and tender-crisp. Drain and immediately transfer to a bowl of ice water to stop the cooking process. Once cooled, drain again and set aside.
In a small bowl, whisk together the olive oil, lemon juice, Dijon mustard, salt, and pepper until well combined.
In a large salad bowl, combine the mixed greens, blanched asparagus, crumbled goat cheese, and chopped hazelnuts.
Drizzle the dressing over the salad and toss gently to combine, ensuring everything is evenly coated.
Serve immediately, or chill in the refrigerator for up to 30 minutes before serving for a refreshing touch.