A grey, steamed sear typically results from insufficient heat, overcrowding the pan, or using meat that is too wet. These factors prevent the Maillard reaction, which is essential for browning.
Achieving a beautiful brown crust, also known as the Maillard reaction, requires a few key elements. First, the pan needs to be sufficiently hot. If the pan isn't hot enough, the moisture from the meat will steam it instead of searing it. Second, overcrowding the pan lowers the temperature significantly. When too much cold meat is added at once, the pan's temperature drops, leading to steaming. Finally, excess moisture on the surface of the meat inhibits browning. The water needs to evaporate before the Maillard reaction can occur. To get a good sear, ensure your pan is screaming hot, pat your meat dry with paper towels before cooking, and avoid overcrowding the pan. Work in batches if necessary. Using a heavy-bottomed pan like cast iron also helps maintain a consistent temperature.
Before searing, consider dry-brining your meat. Salting it generously an hour or two beforehand (or even overnight) draws out moisture, allowing for a much better sear and more flavorful result.