Preheating Isn't Optional for Searing
A pan that isn't fully hot before food goes in won't sear properly — food will steam and stick instead of browning, since a cold or lukewarm surface can't drive off surface moisture fast enough. Give a heavy pan (cast iron especially) several minutes over medium-high heat before adding oil, and test readiness with a flick of water (it should skitter and evaporate almost instantly).
Sources & methodology: These tips draw on established food-science references —
Harold McGee's food-science writing, America's Test Kitchen /
Cook's Illustrated testing, Serious Eats'
technique reporting, USDA food safety guidance,
and peer-reviewed food-safety research (including UC Davis
cutting-board studies) — not reworded recipe-blog consensus.