The main reason food sticks to stainless steel is that it touches the pan while the metal is still not hot enough. Meat or vegetables added too early bond into the microscopic pores on the surface; once the pan reaches the right temperature, that bond releases on its own and the food comes free.
That's why stainless steel needs a few minutes of medium-high heat before anything goes in. A quick water-drop test works well: if a few drops bead up and roll around the pan instead of evaporating instantly, the pan has reached the right temperature.
How much do oil and timing matter?
Cooking without enough oil also makes sticking worse; oil forms a thin layer between the metal and the food that cuts down direct contact. Oil should go in after the pan is hot, and food should follow as soon as the oil starts to shimmer.
Trying to move food right after it hits the pan makes sticking worse too. Proteins like meat or fish form a crust as they cook; a piece pulled before that crust finishes stays stuck, but once the crust is done it releases on its own.
How do you stop a pan from building up stuck-on residue?
To make the next round of cooking easier on a pan with stuck-on residue, wash and dry it thoroughly before use; leftover oil and food bits trigger new sticking. Heating the pan properly and adding oil at the right moment goes a long way toward keeping the bottom from turning sticky again.
If sticking keeps happening, lowering the burner slightly and letting the pan heat longer helps food cook more evenly with less bonding to the surface.
Which foods stick the most to stainless steel?
Delicate proteins like eggs and fish stick to stainless steel far more easily than red meat, since the protein structure on their surface bonds more strongly with the metal. When cooking these in stainless steel, it helps to heat the pan a bit longer and use slightly more oil.
Sugary sauces and marinated meats are also prone to sticking, since the sugar in them caramelizes quickly at high heat and bonds to the pan's surface. These should be cooked over medium heat with closer attention.
Vegetables are generally among the least sticky foods; even so, starchy ones like potatoes can stick in a pan that hasn't been heated enough, so the heating step shouldn't be skipped for them either.
After the water-drop test, food should go in fairly quickly to keep the pan at the right temperature; waiting too long between the test and adding food can let the pan overheat and start smoking. Turning the burner down slightly at this point helps keep the temperature steady.
Washing a hot pan with cold water right after cooking can also create tiny cracks in the surface; letting the pan cool down a bit first both reduces future sticking and extends the pan's life.
The pan's handle needs to hold up to heat too; some models with plastic handles can get damaged if left over high heat for a long time, so paying attention to the handle's material also helps the pan last longer.