Snap off tough ends of asparagus; sprinkle with 1/4 teaspoon salt. Set aside.
Toss potatoes with oil, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Arrange in a single layer in the bottom of a broiler pan coated with cooking spray. Bake at 500° for 10 minutes.
Trim fat from tenderloin. Sprinkle tenderloin with 1/4 teaspoon salt and 1/4 teaspoon pepper. Insert meat thermometer into thickest portion of tenderloin. Add tenderloin to broiler pan, nestling it into potato mixture. Bake at 500° for 20 minutes or until thermometer registers 145° (medium-rare) to 160° (medium), stirring potatoes once.
Place tenderloin and potatoes on a serving platter; cover with foil. Let stand 10 minutes. Add asparagus and water to pan. Bake at 500° for 10 minutes or until asparagus is crisp-tender. Serve with tenderloin and potatoes.