1. Boil pasta in salty water until al dente, about 4 minutes. Drain, rinse with cold water and allow to cool.
2. Combine peas and asparagus.
3. Place sugar and vinegar in a small saucepan and heat until sugar is dissolved; do not boil.
4. In food processor, combine spinach, onion, garlic and herbs, then pulse until blended. Mix with mayonnaise.
5. Combine cooked pasta, vegetables, and mayo-herb mixture and stir well. Add cooled vinegar mixture a little at a time, until a creamy consistency (you may not need it all as pastas vary). Season with salt and pepper. Allow to rest in the refrigerator up to 2 hours or overnight. Toss again before serving and garnish with flaky salt and fine herbs.
NOTE: Add salt to remaining vinegar mixture for a quick pickling mixture.