Bring a large pot of salted water to a boil, then add the pasta. Boil the pasta until al dente, then drain it into a colander, reserving about a half cup of the pasta cooking water. You can proceed to the next step while your water heats up and while your pasta cooks.
Place the cashews, broth, yogurt, lemon juice, and 1 ½ teaspoons of salt into a blender. Blend the ingredients to a smooth liquid. Add the dill and briefly blend again, just until the dill is finely chopped. Set this aside.
Coat the bottom of a large skillet with the olive oil and place it over medium heat. Give the oil a minute to heat up, then add the asparagus. Cook the asparagus for about three minutes, stirring occasionally, until the pieces are bright green and tender-crisp.
Push the asparagus to the side and add the garlic to the skillet. Sauté the garlic while stirring constantly until it becomes very fragrant, about one minute.
Add the cooked pasta to the skillet (Note 1), then add the cashew mixture. Cook the pasta in the sauce for one to two minutes, until everything is very hot. Thin the sauce with the reserved pasta water if it gets too thick.
Stir in the peas, then remove the skillet from heat. Season the pasta with additional salt and black pepper to taste.
Serve.