Step 1

Using a fork, mash the salted duck egg yolks into fine crumbs.

Step 2

Using a spoon mix in butter.

Step 3

Sift in icing sugar, custard powder, and cornstarch. Mix until well-combined.

Step 4

Add in the coconut milk, a little at a time.

Step 5

Refrigerate the custard filling until cold and firm. When firm, use a small ice cream scoop to scoop out and divide the custard into 12 portions.  Place the custard balls on a plate and freeze for 15 minutes until firm. (PS. Any extra filling not used for the mochi is amazing when spread on toast.)

Step 6

Sift together mochiko flour and sugar in a medium sized bowl. Pour in the water and stir until combined.

Step 7

On medium heat, steam mixture for 10 - 15 minutes until dough comes together. Half way through cooking, stir with oiled rubber spatula and cover to finish cooking. The colour of mochi should change from white to almost translucent.

Step 8

Wait for mixture to cool for 15 minutes before handling mochi. Cover the work surface with parchment paper and dust it generously with cornstarch. Transfer the cooked mochi to surface. Sprinkle more potato starch on top of the mochi.

Step 9

Using a rolling pin, roll out the mochi to a thin sheet, roughly a 6 x 6 square. Using a circular cookie cutter, cut out 8 - 10 rounds.

Step 10

Place a chilled custard ball at the centre of the mochi wrapper. Pinch the four corners of the mochi layer together to cover the custard. Pinch the remaining corners together.

Step 11

Roll mochi ball in palms to thoroughly seal and close the mochi opening. Dust with extra cornstarch and set aside, covered. Repeat untill all wrappers are used up.