Heat large pan and melt butter; toss in sliced onions (and other veggies if desired), stirring around until soft and caramel in color (about 6-7 minutes). Remove from pan and set aside. Using the same skillet, increase heat to med-high, add butter and oil, then add steak (lightly seasoned with seasoning salt) in one layer (may have to cook in several batches). Cook for 1-2 minutes then flip and cook for 1-2 minutes on other side. Once beef is browned pour in Jed's NEK Worcestershire Sauce stirring for about a minute. Add onions back into pan and stir into beef. Place cheese on top of beef, cover for one minute, until melted. Meanwhile, heat griddle or another pan, spread a thin layer of butter on cut side of sub roll, toasting (butter side down) until brown. Serve cheesesteak on top of rolls. Enjoy!