A 16oz steak is too thick to treat like a 6oz week-night. If you only use a ripping pan, you get a burnt edge and a raw middle, or you panic and serve grey. Reverse-sear is the calm method: warm it through in a low oven, then colour it hard. Big Daddy Rump Steak 16oz and The Caveman Sirloin Steak 16oz in 16oz steaks are the packs this is for. A 6oz sirloin does not need this palaver.
The oven then the pan
Oven 90°C, steak on a rack, probe until the centre is about 46–48°C for medium-rare after the sear. It can take 30 to 50 minutes depending on starting temperature and thickness. Then a smoking pan, 45 to 60 seconds a side, fat edge rendered. Rest 8 to 10 minutes. Slice across the grain on rump; sirloin can be served in two if you are sharing.
Salt early. Dry the surface before the pan or you will not get a crust after all that patience. Shop rump steaks if you want a 2x 6oz instead of this project. Reverse-sear is for a thick steak and a bit of time, not for a school night unless the school night is unusually civilised.
BBQ version
Indirect heat until the probe number, then onto the coals for a crust. Same rest. Wind will change the timing, which is why the probe is the cook, not the clock. THE BEAST can use the same idea at a larger scale; a 6oz cannot and will dry.
Failure modes
Oven too hot, so it is cooked before you sear. Pan not hot enough, so the crust takes so long the middle overshoots. Rest skipped, so the board drinks the juice. Those three errors are the whole list. Avoid them and a 16oz steak is one of the better things you can serve from a British butcher’s pack.
A probe that you actually look at is cheaper than ruining a 16oz steak. Put it in from the side into the centre. When the number is right, sear, rest, slice. That is reverse-sear without a restaurant word for it, and it is how thick steaks should be cooked at home.
Taste for salt at the end, not from a frightened start. Lean packs need seasoning; glazed packs may already have enough. The pack label is a start, not a complete recipe, and your pan is still the last decision in the kitchen. That is as true of How to Reverse-Sear a 16oz Steak as of any other pack we send out of the cutting room. Cook it like the cut it is, and it will earn the next click.