The day before, soak the beans in plenty of water overnight.

The next day, drain the beans and add them to a saucepan along with the baking soda. Cover generously with water, bring to a boil and simmer for 45 minutes or until so soft that you can easily mash them between your fingers. You can also leave out the baking soda and double the cooking time instead.

Drain the beans but keep the cooking liquid. Tip the drained beans into the bowl of a small food processor and add around 100 ml of the cooking liquid. Then blend into a smooth sauce, adding more liquid if necessary. Tip the blended beans into a non-stick frying pan, add the sugar and cook on low heat for around 10 - 15 minutes, stirring constantly, until the beans have reduced into a thick paste and turned a few shades darker. You want to be able to shape the paste into balls between your hands later on, so make sure to thicken it far enough, but keep in mind that it will also firm up a little more as it cools down. Transfer the paste to a bowl and let it cool off entirely, than cover and refrigerate until needed.

In a sauce pan, combine the sugar with 110 ml water and bring to a boil.

Add the flour to a bowl, make a well in the middle and pour in the sweetened water, then use chopsticks to mix it together, adding more water or flour if necessary. Once it is cold enough to handle, use your hands to knead the mixture into a rough dough. Tip it out onto a clean surface and continue kneading it for a few minutes until smooth. It should be quite firm at this point. Place it back into a clean bowl, cover with a damp kitchen towel and rest for 30 minutes.

In the meantime, spread the sesame seeds onto a shallow plate and have a small bowl of water nearby. With wet hands, roll the red bean paste into 10 balls and set aside. Finally, heat the oil to 130°C.

When the dough has rested, shape it into a log and divide it into 10 similar-sized pieces. Roll each piece into a ball, then cover the shaped balls with the damp towel to avoid them from drying out. Now, one ball at a time, use your thumb to press an indent into the dough and go around the edge with your thumb and index finger to shape it into a cup. If the dough is too soft to hold the shape of a cup, just gently flatten it into a disk. Add a ball of the red bean paste in the centre of the dough and fold the dough around the paste, gently stretching it if necessary to cover the ball. Then pinch the dough closed at the top and roll it between your hands to shape it into a ball again. Continue with the remaining dough.

Dip each ball into the water and immediately roll it in the sesame seeds until evenly coated. It helps to use a teaspoon to lift the dough in and out of the water to avoid your hands from getting wet and the sesame seeds sticking all over. Once the ball is covered in seeds, gently roll it again between your hands to press the seeds into the dough and prevent them from falling off. Set aside on a plate and continue with the rest.

When the oil is ready, add around 4-6 balls at a time. They will double in size later on, so make sure to leave enough space in the pan. Gently fry them for 6-8 minutes while moving them every now and then until they begin to float, then use a spider or slotted spoon to press them back down and keep them submerged. At this point, they will begin to puff up and double in size. Once they have increased in size, crank up the temperature to 180°C and fry them for another 6-8 minutes until beautifully golden. This will ensure that they stay crispy and don’t deflate later on. Then transfer them onto a rack lined with kitchen paper to drain off any excess oil. Let the oil cool down again and continue with the rest. Then serve warm.