Heat a skillet on medium high heat, (I use cast iron skillet) add 2 tablespoons butter and 1 tablespoon olive oil. Add sliced onions. Reduce heat to medium low and cook 15-20 minutes stirring every minute, to prevent any burning. Remove and set aside.
Crank up the skillet to high heat, add 1 tablespoon olive oil. Just when pan begins to smoke add in steaks. Cook 4-5 minutes then flip.
Add in the final 2 tablespoons of butter and allow it to foam. Add in garlic and baste the steaks with the melted butter.
Baste constantly will cooking for another 3-4 minutes for medium rare or until done to your preference.
Serve and spoon pan sauce and onions over steak.