Cooking submerged or half-submerged in hot fat, which transfers heat far faster than air and dries the surface into a crust.
Technique at a glance
A compact visual model of the lesson. Use the full mechanism and success criteria below when you practice.
Concept
Cooking submerged or half-submerged in hot fat, which transfers heat far faster than air and dries the surface into a crust.
What changes
Hot oil conducts heat several times more efficiently than an oven's air, so the surface reaches browning temperature almost immediately.
What good looks like
Vigorous bubbling around the food that slows as it finishes — when the bubbling nearly stops, the water is largely gone and so is the cooking.
Practice counts when you cook
Reading this brief does not change your School state. Finish a real practice dish in Cook mode and log the cook; that cook is the evidence that advances the skill.
What to focus on
Mechanism
Hot oil conducts heat several times more efficiently than an oven's air, so the surface reaches browning temperature almost immediately. What happens next is a race: water inside the food turns to steam and pushes outward, and as long as it is escaping, oil cannot get in — the visible bubbling is that steam, and it is the food defending itself. This is why correct frying is not greasy. When the oil is too cool the surface never seals, steam pressure is weak, and oil soaks in; when it is too hot the exterior sets and colours before the interior has cooked. The working window is roughly 170-190°C for most things. Every batch drops the oil temperature, so the single most useful habit is waiting for it to recover between batches.
Success criteria
Vigorous bubbling around the food that slows as it finishes — when the bubbling nearly stops, the water is largely gone and so is the cooking.
The sound is a steady roar, dropping in pitch as moisture leaves.
Food floats as it dries out and becomes less dense.
Oil shimmers and moves in visible currents at temperature; a cube of bread should brown in about sixty seconds.
Failure guards
Greasy, heavy food.
Oil too cool. Without enough steam pressure pushing out, oil moves in. This is the cause of nearly every greasy fried thing.
Dark outside, raw or cold inside.
Oil too hot, or the pieces too thick. The surface reached its final colour long before heat reached the middle.
Crisp for two minutes, soggy after five.
Drained on paper or a plate, where steam condenses under the crust. A wire rack is the whole fix.