1. Mix the self-raising flour and instant yeast together in a large bowl.

2. To a saucepan, add the soy milk, margarine, sugar and vanilla extract. Place over low heat on the stove, stirring gently until the margarine has melted.

3. Let the mixture cool enough so that it's warm to the touch. You don't want it to be cold but it shouldn't be super hot either.

4. Add the wet mixture to the bowl with the flour and yeast. Mix well to make a super sticky dough.

5. Place the wet dough onto a heavily floured surface and knead until springy, using extra flour as needed. You'll know it's done when you press the surface of the dough and it springs back into place.

6. Place the ball of dough into a lightly oiled bowl and cover with clingfilm or a clean dishcloth. Put the bowl in a warm place (like the inside of a switched-off oven) for exactly 1 hour.

7. After the hour is up, roll out the dough on a lightly floured surface until ½-inch thick. Use a 3-inch cookie cutter to cut out your donuts, rerolling as needed. You should get 8-10 in total.

8. Place the rounds of dough onto a non-stick tray or plate and cover for 1 more hour until puffy. This will ensure your air fryer doughnuts are nice and fluffy!

9. Grease your air fryer basket with cooking spray or vegan margarine and preheat to 180℃ for a few minutes.

10. Air fry the donuts in small batches for 10 minutes each, flipping them over halfway.

Coating:

1. While the donuts are still warm, brush them with the melted margarine then roll them in the caster sugar.

Filling:

1. Use a skewer or metal straw to poke a hole into the donuts, gently wiggling it around a little to make room for the filling.

2. Place the custard into a piping bag fitted with a small nozzle. Pipe it into each donut until nicely filled.