Food sticks to stainless steel when heat, surface moisture, and fat are poorly balanced. Moderate preheating and allowing proteins to form a crust before moving them usually makes the biggest difference.
Preheat without overheating the pan
Heat over medium and adjust for the food. A pan that is too cool encourages sticking; one that is too hot burns fat and the food surface.
Dry the food surface
Surface moisture cools the pan and delays browning. Pat meat, fish, or tofu dry before adding it.
Add suitable fat and wait
A thin film of oil helps separate surfaces. Once a protein browns, it often releases more easily than if you try to move it immediately.
Fond is not the same as burned food
Browned bits stuck to the pan can become a sauce when deglazed. If they are black and bitter, the heat was too high or the cooking time too long.