Mix the Dry Ingredients: In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, and sugar. Make sure everything is well combined.
Add Wet Ingredients: Pour in the lukewarm water and 1 tablespoon of vegetable oil.
Form the Dough: Gently mix everything with a spatula or your hands until a shaggy dough forms. Don't overmix it at this stage. It's okay if it looks a little rough.
First Rest: Cover the bowl with plastic wrap or a damp kitchen towel and let the dough rest at room temperature for about 30 minutes.
Knead (Briefly!): After 30 minutes, lightly flour your work surface and gently knead the dough for just 1-2 minutes. It should become smoother.
Second Rest (Long Rest): Place the dough back in the bowl, cover it again, and let it rest in the refrigerator for at least 2 hours, or even better, overnight.
Shape the Youtiao: The next day (or after at least 2 hours), take the dough out of the fridge. Gently stretch it into a long rectangle, about 1/2 inch thick.
Cut into Strips: Use a knife or a pizza cutter to cut the dough into strips, about 1 inch wide.
Pair the Strips: Take two strips and place one on top of the other.
Press Together: Use a chopstick or the back of a knife to press down the center of the stacked strips, lengthwise.
Heat the Oil: In a large, deep pot or wok, heat about 2-3 inches of vegetable oil to 350-375°F (175-190°C).
Stretch and Fry: Gently stretch one of the paired, pressed dough strips to about double its length. Carefully lower it into the hot oil.
Fry Until Golden: Fry the Youtiao, turning it frequently with chopsticks or tongs, until it's golden brown and puffed up. This should take about 2-3 minutes.
Drain: Remove the fried Youtiao from the oil and place it on a wire rack or paper towels to drain excess oil.
Repeat: Continue stretching, frying, and draining the remaining dough strips.