Japanese Boiled Peanuts

Peanuts may not be the first thing to come to mind when you think of a rural Japanese farm stand, but that's exactly what I found last week at a mujin hanbaijo (unattended sales stand). It was literally an old bookcase stuffed with bags of fresh produce, and a wooden box with a slit on top to drop in your money. They had bags of several varieties of autumn eggplant, but what caught my eye were two bags of peanuts that were so fresh, they still had damp coffee-colored soil clinging to the pods.

Peanuts reached Japan through China during the Edo period, and by 1876 they were being grown in Chiba prefecture. It now produces most of the country's crop, and around Yachimata, freshly dug peanuts are simmered in their shells to make yudé rakkasei (boiled peanuts) where it's a seasonal delicacy. Kinda like the fall version of edamame.

The kernels still hold a lot of moisture, so they don't have the toasty nuttiness or crunch of roasted peanuts. What you get instead is the familiar earthy aroma with a fresh vegetal edge. Boiling them gently softens the legumes to a rich, creamy texture while the saltwater slowly permeates the shells, giving them a balance of umami, salt, and sweetness.

The firm shells slow the brine's path to the kernels, so I use a fairly strong 3% salt solution. As the peanuts cool in the cooking liquid, air and steam inside the pods contract, which helps draw in more brine. That rest also gives the salt time to reach the kernels. I also add a little baking soda to the water to raise the pH and help the cell walls soften, which gets the kernels to that creamy texture sooner than boiling them in plain water.

Fresh peanuts vary in size and freshness, so I start checking after 40 minutes; mine were ready at about 45. If you have leftovers, shell and refrigerate them. You can add them to stir-fries or a pot of rice.