When you cook a steak, the goal is to get it evenly browned on the outside while keeping the inside juicy and pink. But sometimes, no matter how carefully you cook it, your steak can end up looking grey.
There are a few possible explanations for why this happens. One is that you simply overcooked the steak and it's now dry and tough. If this is the case, there's not much you can do to salvage it. Sorry!
Another possibility is that the fat in the steak wasn't properly rendered before you started cooking it. When you cook a steak, you want to start by heating up a pan until it's very hot. Then, add some oil or butter to coat the bottom of the pan. Once the fat is melted, add your steak to the pan.
If there's too much fat on your steak (or if you didn't let it heat up long enough), then that fat won't render properly and will instead seep into the meat, making it look grey. In this case, you can try cutting off any visible chunks of fat and cooking the steak for a bit longer until all of the fat has rendered out.
Finally, it's also possible that your meat was just really dark to begin with! Some cuts of beef are naturally darker than others due to different muscle composition or marbling (the amount of fat running through the meat). If this is what happened, then there's not much you can do except enjoy your delicious dark steak!