In a mixing bowl, combine the flour, baking powder, baking soda, and salt.

In a separate bowl, mix the cold milk with the oil. Pour this into the dry ingredients.

Knead in the bowl until a dough ball forms. Cover and rest for 30 minutes.

Lightly oil your work surface.

Transfer the dough onto the surface and gently press it into a rectangle.

Fold the left side into the centre, then fold the right side over it. Flatten into a rectangle again.

Repeat this folding process two more times.

Cover and allow the dough to rest for 1.5 hours.

Add all prawn mousse ingredients into a food processor.

Transfer the mousse into a zip-lock bag placed inside a tall cup. Seal and set aside.

Stir the ketchup and Kewpie mayo together in a small bowl. Set aside.

Lightly dust your bench or mat with flour.

Transfer the rested dough onto the surface. Gently flatten and stretch it into a long rectangle.

Cut into 10 rectangles, each about 3-4 cm wide.

For 5 pieces only, run a faint line of water through the centre using a wet chopstick.

Place the remaining 5 pieces directly on top to form pairs.

Press a chopstick gently down the centre of each pair to seal only the middle. Note: the sides should remain separated so they can puff.

Heat vegetable oil in a wide pan to 200°C / 392°F.

Take one dough pair, stretch it to twice its length, and gently lower it into the oil.

Fry, rotating continuously with chopsticks or tongs so it puffs evenly.

When lightly golden, remove and drain on paper towels. Repeat with remaining pieces.

Cut each youtiao into 6 bite-sized pieces.

Pull out some of the soft interior to make room for the filling.

Snip off the corner of the prawn mousse zip-lock bag and pipe filling into each piece.

Arrange the stuffed pieces in a single layer in a lined air fryer basket.

Air fry at 170°C for 15 minutes, or until the prawn filling is fully cooked through.

Transfer to a bowl and toss with the ketchup-mayo sauce.

Garnish with chopped parsley and serve immediately.