Trim fat from tenderloin steaks. Gently press crushed green peppercorns into both sides of steaks; let stand at room temperature 20 minutes.
Coat a large nonstick skillet with cooking spray; place skillet over medium-high heat until hot.
Add watercress, and cook, stirring constantly, 1 to 2 minutes or until watercress wilts.
Remove watercress from skillet; set aside, and keep warm.
Coat skillet with cooking spray; place over high heat until very hot.
Add steaks, and cook 6 to 8 minutes on each side or to desired degree of doneness.
Remove steaks from skillet. Set steaks aside, and keep warm.
Remove skillet from heat; add Cognac, and ignite with a long match. When flame dies down, add beef broth and salt. Bring to a boil; reduce heat, and simmer 2 to 3 minutes or until broth mixture is reduced by half.
Place watercress evenly on 4 individual serving plates; place steaks on watercress.