Yes you can slow cook steak.
Steak is excellent slow cooked. It needs to be done at a very low temperature. Around 50 degrees celcius for 18 hours or 75 degrees for about 9 hours, even up to 100 degrees for about 4 hours. It results in a very tender piece of meat. Yes, steak tends to be the more tender cut of meat, but age, quality, handling and even cooking can make it go tough.
Bring the meat to room temp. Pre-heat oven and put meat on a rack over a tray. Slow cook. After the time period, it shouldn't really look cooked at all, but will be firmer. Heat a fry-pan to a medium high heat. Brush the steak with a little oil and season. Brown on both sides and serve. Perfect!!!