Microwave the shiro-an for 1 minute at the highest setting. Tear the gyuuhi into small pieces and knead into the shiro-an with a spoon while mashing the pieces.
Microwave for another 30 seconds. When the mixture is smooth, cool it down completely.
The basic nerikiri is done when it doesn't stick to your fingers when you pinch it. If it's too soft and sticky, repeat Step 2.
You can color the nerikiri by adding drops of food coloring and kneading it in until the dough is evenly colored.
I divided the dough into 3 portions, and colored one pink and another one green.
To make a nerikiri plum flower: Divide the light red (pink) and white balls of dough in half. Wrap the pink dough around the white dough, using more pink dough than white as shown here.
When the pink dough is wrapped around the white dough, roll the ball in your hands until the seam disappears. It's OK if the white dough shows through a bit.
Mark the top and sides of the dough with a spoon. If you can get the white dough to show through a bit, it will have a gradated effect and will be very pretty.
This is user "Risunoshippo"'s creation, hedgehogs. She colored the nerikiri with cocoa powder and cinnamon powder, and made the needles with scissors! So cute.
Story Behind this Recipe
Authentic nerikiri has to be cooked and burns easily, and is a bother to make, so I thought up an easy method. The shiro-an is made with "Po"'s recipe with less water, that I always have stocked in the freezer.
If you are using homemade shiro-an and/or the shiro-an you're using is watery, I recommend microwaving it for 2-3 minutes in Step 1 to evaporate off the excess moisture. The nerikiri sticks to the spoon and becomes harder to handle when it cools down, so work quickly while it's still hot. If you flatten the ume plum flower it will be like one in bloom, and if you make it round it will be like a flower bud. If the surface of the nerikiri dries out it will turn yellow and not taste that good. Either cover tightly with plastic wrap and freeze, or eat the day you make it.