Crush gardenia fruit and wrap them in gauze or tea bag. Set it aside.
In a large pot, combine water and sugar for the candied chestnuts and bring to boil.
Add whole chestnuts, mirin, salt, and crushed gardenia fruit in tea bag (or a drop of yellow food color) to the pot. Bring the heat to low and cook for about 15 minutes. Skim foam off the surface if necessary.
Keep 4 tablespoons of the syrup from the pot and drain. Set them aside.
Peel the skin of the sweet potatoes and cut into 1-inch chunks. Leave in water for about 5 minutes.
In a large pot add plenty of water, sweet potatoes, and crushed gardenia fruit in tea bag (or 1-2 drops of yellow food coloring). Boil until potatoes are soft.
Strain the potatoes while they’re still hot and put it back in the pot.
Add all of the ingredients of the seasoning and cook over medium heat. Stir with wooden spoon and cook until potatoes turn into a thick paste.
Stop the heat, and spread the mixture on a tray to cool down.
Place the potato mixtures back into the bowl. Cut the chestnuts into halves, and gently mix into the potato mixtures. Serve.
Kuri kinton https://www.umami-insider.com/recipe-kuri-kinton/