How do I know when oil is hot enough to fry?

The most reliable method is using a thermometer, aiming for 350 to 375 degrees Fahrenheit for most frying. If you don't have one, dip the handle of a wooden spoon or a wooden chopstick into the oil. If small bubbles form steadily around it, the oil is ready. You can also drop in a small piece of the food you're frying, and if it sizzles immediately and floats, you're good to go. Another common trick is the water drop test, but be careful as water causes hot oil to splatter. The wooden spoon method is safer and quite accurate. Avoid letting oil smoke, as that means it's too hot and starting to break down.