Use medium heat, don't overcrowd.

Keep the burner at medium to medium-high rather than maximum. Excessively high heat scorches the oil and the meat surface before a proper crust can form, causing it to weld to the pan. Equally important, leave space between pieces -- each piece should have at least 2 cm of clearance. Overcrowding drops the pan temperature rapidly, and the released moisture turns to steam, making the meat stew instead of sear. Cook in batches if necessary, allowing the pan to recover heat between rounds.