Form the dough into a ball, put it back in the bowl, cover with plastic wrap, and let it rest at room temperature for at least 30 minutes or longer. Letting the dough rest increases its elasticity making easier to work with later, so please don't skip.
Add miso and julienned shiso leaves, and mix well together. Transfer to a dish to let cool.
Cut the kabocha into smaller wedges and remove the skin (See How To Cut a Kabocha Squash).
Transfer the oyaki to a steamer basket and cover to cook on high heat for 15-20 minutes (depending on the size of the oyaki and filling – small one should take about 10 minutes). Make sure the lid is covered with the kitchen towel so condensation on the lid doesn’t fall onto the oyaki.
Enjoy them immediately. As soon as they become warm, not hot, cover the leftovers with plastic wrap (I wrap individually). Don’t wait until completely cooled down. You can freeze to store for up to a month, and re-steam to enjoy later.
Sugar: I'm aware that 1 Tbsp of sugar seems a lot. However, the dough tastes rather simple and bland, and the taste of good oyaki relies on the fillings' flavor. I highly recommend to season the fillings well. For kabocha filling, if you prefer more savory taste, you can increase the amount of soy sauce but you will need to add some sugar to balance out the salty flavor and can't omit it completely.
Recipe by Namiko Chen of Just One Cookbook. All images and content on this site are copyright protected. Please do not use my images without my permission. If you’d like to share this recipe on your site, please re-write the recipe in your own words and link to this post as the original source. Thank you.