In a large bowl, add in your dried lotus seeds, and then fill the bowl with enough water to cover all of the lotus seeds plus an extra 2 inches above the lotus seeds.
Allow the lotus seeds to soak overnight in the fridge.
The next day, strain out all of the water and give the lotus seeds a quick rinse.
Now open the lotus seeds and take out the green stem in the core if you see any. If you don’t remove the green stems, they will make your lotus seed paste very bitter. You can save these green stem cores for brewing tea if you’d like.
Once done, give the lotus seeds another quick rinse and then add them to a pot with water. Boil the lotus seeds on medium heat in the pot until there is about 1/2 inch of water above the lotus seeds. Now turn down the heat to medium-low/ low-heat and continue cooking the lotus seeds until they become soft. This will take a while, so be prepared. It took me about an 1 hour to cook the lotus seeds over the stove.
To check when the lotus seeds are ready, scoop up 1-2 lotus seeds and press down on them with your finger. The lotus seed should easily break and become mushy if it has reached the right softness level.
Once done, remove the pot from the stove and allow it to cool down.
Now transfer all of the contents of the pot, including the leftover water to a blender.
Blend everything together until the lotus seeds become a smooth paste. If you find the lotus paste too thick, then add an additional 1-2 Tablespoons of water to the blender and continue blending it until nice and smooth. It should have a consistency similar to peanut butter.
Once done, transfer the contents into a bowl and set the lotus paste aside.
Now, add 3 tablespoons of cooking oil along with your white sugar to a non-stick pan and cook it over medium-low heat while constantly stirring the pan. Continue cooking the mixture until all of the sugar has melted and caramelized. You should have a nice brown color syrup in the pan.
Now, add your blended lotus paste to the pan and mix everything well together with the oil and caramelized sugar.
Next, add in your leftover cooking oil in 3 stages. Add about a 1/3 of it into the pan and mix it well together with the lotus paste. Once all of the oil has been absorbed, add in another 1/3 of it and mix it well with the lotus paste until all of it has been absorbed. Then, add in the remaining 1/3 of oil and repeat the process.
Once all of the oil has been absorbed by the lotus paste, add in your maltose and mix everything well together.
Continue cooking this mixture over medium-low heat until most of the water has evaporated and the lotus paste doesn’t stick to your spatula or pan anymore. It should resemble one large piece of filling. Do not overcook the filling, or it will become dry!!!
Remove the filling from the stove and pour it into a bowl or container.
Let it cool down, and then cover it with plastic wrap and place it in the fridge to chill.
The lotus seed paste is now ready to use.