Wash the sesame seeds and walnuts
Drain out the water and set them aside.
Then add them to a frying pan or wok and toast them on low to medium-low heat until the white sesame seeds change color to a beige color and the sesame seeds become aromatic. It should take around 8-10 minutes. You might start to see the sesame seeds start to jump up too when they are ready.
Once done, remove them from the wok and let them cool down.
Next, add the sesame seeds, walnuts, white sugar, lard, and water into a blender or food processor.
Blend everything together until it reaches a fine, semi-liquid texture.
Once done, transfer everything to a flat container covered with plastic wrap. The plastic wrap will make removing the filling a whole lot easier.
Cover the container and let it freeze for at least 1 hour in the freezer so that it solidifies.
Now, take the container out and divide the black sesame filling into balls that weigh about 10g each. You should get about 29 pieces in total.
Cover the black sesame balls, and let them freeze for another hour or two, or until they’re frozen solid. Don’t take it out until you’re ready to start wrapping the tang yuan, as the filling melts quickly.