Zunda Mochi (Rice Dumplings in Sweet Edamame Paste)

Variations

• Pounded mochi: the original uses rice that is steamed and pounded, pulled off in bite-sized pieces. Shiratamako dumplings are the quick home route, and they stretch for the same reason — daifuku puts that down to one number, the amylose.
• Broad beans: zunda is also made from broad beans instead of edamame. Their inner skins are much thicker, so the skinning step matters even more.
• Kurumi mochi: the same region's version, with ground walnuts in place of the edamame.
• Sieved smooth: push the mashed beans through a sieve for a smooth zunda — the same fork in the road that splits koshian from tsubuan in red bean paste. The coarse one is the traditional one.
• On other things: zunda goes over plain dumplings, ice cream, and into milk as a drink. Whatever it goes on, the premise is that it is eaten the day it is made.

Tips

• It is a bean paste, but from the other side of the drying line. Red bean paste starts from a dried pulse, and most of the rules attached to it follow from the drying. Soaking throws the water away because "the indigestible oligosaccharides leach into it"; monaka and yokan discard the first boil and then simmer an hour. Edamame is the soybean picked before it ripens and dries, so it follows the vegetable rules instead: no soak, no discarded water, a few minutes.
• So the rules come from blanching. The conclusion that guide draws in its first section is this dish's first step: "cook briefly, dilute the acid, and give the acid a way out". Plenty of water, the lid off, salt in it, and stop at four or five minutes. The green is what the paste is named for.
• The same soybean left to ripen and dry is kongguksu. That page soaks its beans six to eight hours before boiling, and it gives the reason for the skinning too: "The skins are where the astringency and the gritty texture come from." Edamame skins are much thinner, but mashed into a paste they leave the same grit.
• Why the sugar can go in all at once. Monaka adds its sugar in three goes, because added at once "osmosis pulls water back out of the beans and toughens the skins irreversibly". That happens to beans still in their skins, cooking in a syrup. Zunda's inner skins are off before the sugar arrives and there is no heat under it, so neither half of that reason is present.
• Never cooked down, so it cannot be wrapped. Daifuku says the filling has to be dry, and adds that red "bean paste has already been cooked down, which is why it causes no trouble". Zunda is exactly the other case: none of the beans' own water has been driven off, and the sugar has only dissolved into it. Wrap it in mochi and the seam goes wet and opens (wrapping and sealing). That is why this sweet puts the paste over the dumplings rather than inside them — the shape and the water go together.
• It keeps a day for the same reason. Yokan's sugar leaves so little free water that "it keeps over a year at room temperature". Zunda's sugar is about a quarter of the bean weight and nothing was reduced, so sugar is not preserving it. Eat it the day it is made; left over, a day in the fridge is the limit. The paste alone can be frozen.
• Coarse is not lazy. A few bits of bean are what set it against the smooth mochi. Blended to a purée, that contrast is gone. Without a mortar, bag the beans and press them with the bottom of a jar.
• Keep the pinch of salt. With this little sugar, it is the salt that brings the bean flavour forward (salt and seasoning).