I have been wanting to try this forever, and even got so far as to buy a bag of shelled edamame and throwing it in the freezer, where it has stayed for the last month or so. I finally got my break yesterday, and making them couldn’t have been easier.
I used a ten-ounce bag, just about 2 cups of beans. Defrost—the best way is to just run them under water then pat dry. Spill them onto a rimmed baking sheet and put them into a 400° oven until they start to get a bit crunchy/chewy and start to brown, which will take about 30 minutes. (If you want to get them really crunchy, dial the heat down to 350° or even 325°. At these lower temps, you can get the edamame drier before they get too brown. Check on them every 10 to 15 minutes after the first half hour—it might take up to an hour to get them to the degree of crispness you want, depending on the temperature you use).
While the edamame are roasting, stir together 1 teaspoon salt and 1 tablespoon wasabi powder. (If you like a little more saltiness, you can up the salt to 2 teaspoons; and if you’re worried about heat, add the heat incrementally.) A word about wasabi powder: Buyer beware. A lot of the stuff sold in American markets is not true wasabi—it’s powdered horseradish mixed with dry mustard and artificial coloring. While horseradish and wasabi both belong to the cabbage family, their flavors are not the same. For the real-deal 100 percent ground wasabi that will clear your sinuses and grow hair on your chest, look for jars marked “pure namida.” You may very likely have to order it online.
When the edamame are a bit shy of the degree of brownness and crunch you want, take them out of the oven. Immediately drizzle 2 tablespoons good quality vegetable oil or sesame oil over them, toss to coat, sprinkle them with the wasabi mix, and again toss to coat them evenly with the powder. Then return the pan to the oven to bake the coating onto the beans and brown them a bit more; figure another 10 to 15 minutes. (If you baked the edamame at a lower temperature initially, up it to 400° for this step.) Once out of the oven, enjoy them hot, warm, or at room temperature; these are best eaten the day they are made.