You tiao (油条, literally oil stick or oil strip) are the long, golden, slightly crispy-on-the-outside, airy-on-the-inside Chinese fried dough sticks that are one of the most ubiquitous breakfast foods across China, eaten alongside congee, soy milk, or wrapped in cheung fun rice noodle rolls. They are made from a yeasted dough with a chemical leavener (traditionally alum — aluminium sulfate — which is increasingly replaced with aluminium-free baking powder in modern recipes) that is deep-fried in pairs, the two sticks pressed together at the center expanding away from each other as they fry, producing the characteristic double-stick shape.
The alum-free dough: 300g bread flour, 4g instant yeast, 4g baking powder, 3g baking soda, 5g salt, 5g sugar, 200ml warm water, 15ml neutral oil. Mix all dry ingredients. Add water and oil. Mix until combined — do not over-knead. Rest 1 hour. The dough should be soft, slightly sticky. Refrigerate overnight (the cold rise produces a better flavour and more controllable dough). The frying: Oil must be at 190-200C. Pull a strip of dough approximately 30cm long by 5cm wide. Place a second identical strip on top. Press a chopstick firmly down the center (lengthwise) — this creates the weak point at which the two strips will inflate away from each other during frying. Drop the pair into the oil. Use chopsticks to constantly turn it — the you tiao should be turned every 5-10 seconds to ensure even expansion and browning. Total fry time: 2-3 minutes until deep gold and puffed. Texture: A correctly fried you tiao should be golden brown all over, hollow in the interior, with a thin crispy exterior that gives way to an airy, slightly chewy interior.
Insufficient oil temperature: You tiao frying at 160-170C instead of 190-200C will not expand properly — they become dense, oily, and under-airy. Insufficient resting of the dough: A well-rested dough (especially after refrigeration) is much easier to stretch and handle.
Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009); Ken Hom, Complete Chinese Cookbook (2011)