How to clean a flat top grill, restaurant-style

This vaguely comports to the methods I saw and knew in 1990s London. The proper way was to start with oil and use a grill brick [Amazon], but the reality is you will still need lots of environmentally unsound liquids. The mystery degreaser is Swisher but Ecolab is exactly the same stuff and widely available. Wear gloves. Never eat out.