Any wisdom on getting the good crust on thinner cuts with fast cook times?
Crust and grill marks are not exactly the same thing. But they are related. Let's do the thermodynamic science to answer your question.
What you are asking about generally is the browning of the outside of the meat.
The best/most efficient method for outside browning is conduction -- meaning hot metal in direct contact with the food. Conduction is why/how you get grate marks. Because the hot metal grates touching the food brown faster than the hot air touching the food in between the grates.
If you want an all over crust/browning (rather than just stripes) using conduction, then cook on a griddle or a cast iron pan rather than on hot grates. Perfect example is how crusty the outside of a thin smash burger gets in no time at all when cooked on a flat top.
Another example is the story of how "black and blue" or "Pittsburgh rare" steaks started. Steel mill workers would supposedly throw a steak on the metal side of a 2,000 °F blast furnace, leave it for a few moments, and then turn it. The steak was charred/seared outside but raw inside.
Second best is thermal radiation aka infrared light energy. Charcoal grills cook mostly via radiation when in direct mode. Given the big IR from the charcoal, you can still get excellent browning even when using very thin metal grates. Gas grills have low IR, which is why some gassers add extra IR burners for better searing/browning.
Gassers cook mostly by convection -- flow of hot air over the food. Convection is the weakest for browning. So browning a thin cut on a gasser is sub-optimal.
So the best answer is to cook your thin cuts in a method that is mostly conduction or radiation. To get better browning from my gasser, I sear on an add-on griddle (actually the flat side of GrillGrates) covering half the grill top. Or you can cook direct over live charcoal. Or you can use an IR burner.
Cranking up the convection heat on a conventional gasser probably won't brown fast enough if you have a short cook time with a thin cut.
You can also try doctoring the surface with oil, butter, etc. But using a browning forward energy transfer method is the best way to go.
Meathead explains further:
Learn about thermodynamics: the basis of all cooking! Find out how heat transference works in your grill, bbq, and smoker.
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