1.In A Small Bowl, Combine The Spinach, Mayonnaise, Mustard, Lemon Juice And Garlic Salt; Cover And Refrigerate Until Serving. 2.Pour Water Into A Pressure Cooker. Place Salmon On Rack; Sprinkle With Lemon-Pepper And Top With Lemon Slices. Close Cover Securely; Place Pressure Regulator On Vent Pipe. Bring Cooker To Full Pressure Over High Heat. Reduce Heat To Medium-High And Cook For 2 Minutes. (Pressure Regulator Should Maintain A Slow Steady Rocking Motion; Adjust Heat If Needed.) 3.Remove From The Heat. Immediately Cool According To Manufacturers Directions Until Pressure Is Completely Reduced. Discard Lemon Slices. Serve Salmon With Spinach Sauce.