Completely peel the sweet potatoes, and rinse in water. Crack the gardenia seed open, and add it to the sweet potato pot, add the purple sweet potatoes to another pot, and boil until you can poke through with a skewer.
Take both varieties of sweet potatoes out of their respective pots, add 20 g salt to each, and mash with either a hand mixer or a fork.
Add syrup to both varieties of sweet potato and mix, but make adjustments so that it doesn't become too soft. Wrap each sweet potato variety in cloth or plastic wrap along with the candied chestnuts, and squeeze.
Top with sugared red beans or gold leaf to your liking, and it is done.
I added it to my osechi.
Story Behind this Recipe
I love this color combination, and I also make both the western sweet potato kinton and Japanese-style chestnut kinton.
Add to bento or osechi, or give as an attractive present to make someone happy.
You can either steam or microwave the sweet potatoes, but the water content will go down a bit so please adjust it with syrup.
This will turn out pretty if you mix it smoothly in Step 2. Firm mixtures produce stark color contrast.
Using the gardenia seed is optional, and you can use powdered purple sweet potato as well.