To make the dressing, whisk together all of the dressing ingredients in a bowl. Allow the dressing to chill in fridge while you prepare everything else.
Bring a large pot of water to a boil. Add the asparagus and peas, and blanch for 3 minutes, or until the thickest pieces of asparagus are just cooked. Drain the asparagus and peas, and immediately transfer to an ice bath. Drain well, and layout on a cutting board or baking sheet. Dry well with a kitchen towel. Add the asparagus, peas and chopped spinach to a large bowl.
Cook the pasta according to directions, until al dente. Drain the pasta, rinse with cool water, and transfer to the bowl with the vegetables.
Pour the dressing over the pasta and vegetables, and toss well. Season generously with sea salt and freshly ground pepper (see notes.)
Add red onion slices and pine nuts. (I like to toss ½ into the pasta salad, and sprinkle the rest on top.)
Notes
Both asparagus and unwashed spinach can be sandy. To clean these vegetables thoroughly, place them in a very large bowl of water and mix them around a bit with your hands, allowing the dirt to fall to the bottom.
You don't want the pasta salad to be watery! Thoroughly and gently dry the spinach, asparagus and peas with a clean kitchen towel .
This is a lightly dressed pasta salad, so I recommend seasoning well with salt & pepper.