In a large mixing bowl, combine the flour, sugar, and yeast, mixing thoroughly to evenly distribute the dry ingredients. Gradually add the lukewarm soy milk, water, margarine, and egg while stirring continuously until a sticky dough begins to form.

Knead the dough using a stand mixer fitted with a dough hook for about 5 to 10 minutes, or until the dough turns smooth, elastic, and slightly fluffy. If kneading by hand, use the palms of your hands to push the dough down and away, fold it over itself, and repeat the process. Continue for approximately 10 minutes until the dough no longer clings to your hands and develops a supple texture.

Shape the dough into a ball and transfer it to a large, lightly greased bowl. Cover the bowl with plastic wrap or a clean kitchen towel. Allow the dough to rise in a warm environment until it has doubled or tripled in volume, typically around 2 hours depending on the ambient temperature. Positioning the bowl near a warm area or using a low-heat oven (120°F/50°C) can speed up this step if needed.

Once the dough has risen, transfer it onto a floured surface. Roll it out to about ½ inch thickness. Using a glass or a round cutter approximately 3 inches in diameter, cut out as many rounds as possible. Re-roll the remaining scraps and continue cutting until all the dough is used.

Place the shaped donuts onto a floured or parchment-lined tray. Cover loosely and let them rest for about 30 minutes, during which they will puff up again.

Heat 2 cups of oil in a medium pan over medium-low heat. Once the oil is ready, gently fry the donuts in batches, 1–2 at a time, for about 1–2 minutes per side until golden brown. Be cautious not to overcrowd the pan, as the donuts expand during frying and can stick together.

Once all donuts are fried and slightly cooled, prepare the chocolate filling. Melt the chocolate carefully in the microwave, heating it in 30-second intervals and stirring between each session to avoid burning.

Using a chopstick or skewer, poke a hole into the side of each donut to create space for the filling. Fill a piping bag—or a DIY piping tool made with a plastic bag and a short straw— with the melted chocolate. Insert the straw or piping tip into each donut and gently squeeze the chocolate filling inside until it starts to ooze slightly from the entry point.

Repeat the process until all donuts are generously filled. Serve warm for the ultimate melt-in-your-mouth experience or let cool to enjoy later.