Make the dressing. In a medium bowl or 1-cup liquid measuring cup, add the pesto, lemon juice, and zest. Whisk to combine. Slowly drizzle the olive oil in, whisking vigorously as you drizzle to emulsify the dressing, until fully combined. Taste and add salt and pepper, adding more or less than listed depending on your preference.
Boil the pasta. Over high heat in a large pot, add 4 quarts of water, the 2 teaspoons of salt, and bring it to a boil. Boil the pasta until al dente according to package directions. Remove the pasta with a slotted spoon, leaving the water in the pot.
Bring the water back to a boil, then add the asparagus and cook for 2 minutes, or until the asparagus is vibrant green and a little tender. It should still have a lot of crunch to it! Once the asparagus is cooked, remove from the pot, then put into a medium bowl filled halfway with ice and water to stop the cooking.
Cook the frozen peas in the microwave following the package directions.
Assemble the salad. Add the pasta, asparagus, green onion, frozen peas, feta, and parsley to a large bowl. Add the dressing, then stir to combine. Enjoy!