Bring a large pot of salted water to the boil. Add pasta and cook according to package directions. Drain, rinse with cold water, and let cool.
Place eggs in a small saucepan and cover with cold water. Add 1 tbsp of vinegar then bring to the boil. Once boiling set a timer and hardboil for 5 minutes. Remove eggs with a slotted spoon, run under cold water, peel, then slice into halves.
Soak diced red onion with remaining vinegar in a small bowl. Drain and rinse when ready to serve.
In a large bowl toss pesto through the pasta. Add red onion, asparagus, feta and hard boiled eggs. Top with mini leaf basil and hazelnuts.
Serve immediately, or pack up for a deluxe picnic.