In A Skillet, Cook Beef And Onion Over Medium Heat Until Meat Is No Longer Pink; Drain. Add Sauerkraut And Cheese; Mix Well. Unroll Crescent Roll Dough And Separate Into Rectangles. Place On Greased Baking Sheets; Pinch Seams To Seal. Place 1/2 Cup Beef Mixture In The Center Of Each Rectangle. Bring Corners To The Center And Pinch To Seal. Bake At 375 Degrees F For 15-18 Minutes Or Until Golden Brown.