Bring a large pot of water to a boil for pasta. Cook pasta to al dente according to package, about 7-8 minutes. Slice asparagus in 1-inch pieces on an angle. Cut beans into thirds, also on an angle. Midway through cooking the pasta, add asparagus and beans to water so they cook 3-4 minutes in boiling water with the pasta. Add peas to the pot 1 minute before draining. Reserve about 1/2 cup starchy cooking water just before you drain the pasta.