Preheat An Outdoor Grill For Medium-High Heat. Lightly Oil Grill Grate, And Place About 4 Inches From Heat Source. Lightly Brush The Swordfish Steaks And Mango Slices With 1 Tablespoon Olive Oil. Cook The Swordfish Steaks On Preheated Grill Until Lightly Browned On Both Sides, Turning Once, 5 To 7 Minutes Per Side. After Turning, Arrange Mangos Slices Over The Steaks, And Cook 5 Minutes More. Toss The Spinach, Tomatoes, And Kumquats Together In A Bowl. Whisk Together 1/3 Cup Olive Oil And Balsamic Vinegar In A Small Bowl Until Well Blended. Pour Over The Spinach Mixture And Toss To Coat Evenly. To Serve, Divide The Salad Among 4 Serving Plates, And Top With Swordfish And Mangoes.