A few weeks back I collected 40 black walnut fruits at the farm where we get our CSA. This is the eastern American black walnut, Juglans nigra. (The usual kind I see in stores is English walnut or Persian walnut, Juglans regia.) I smashed off the husks to make dye (perhaps more on that another time) and dried the nuts inside for food. Today I finally smashed them open, collecting a little over a half cup of nutmeats. I made two remarkable discoveries:
- They taste pleasantly like blue cheese
- They don't hurt my mouth
Normally If I eat English walnut I find that my mouth starts to hurt, as if I had eaten pineapple after tortilla chips. If I toast them, they're safe. I don't know if it's an allergic reaction or just chemical, but I usually avoid walnuts as a result because they're annoying to toast. However, these I'm able to eat raw with no trouble. So that's neat! But it's not a straightforward swap, because the flavor is different.
I hadn't known to expect the flavor, and it was a bit of a shock. When I cracked the first one and gave it to my spouse to taste (because I didn't know yet that a raw one wouldn't hurt my mouth) she screwed up her face and said she thought it was moldy. Some nuts had developed a little mold on the outside of the shell while drying, and various websites warned about mold and improper storage. But I cracked a fresh, perfect nut and it had the same flavor, or even more so. The flavor is described on various websites as "bold", "earthy", and "more flavorful than English walnut" but none of them had mentioned blue cheese. With a little more digging, I found descriptions like "pungent" or "stinky feet" and I knew this was what they were talking about. (In some cases people described it as "bitter" although this seems to be a genetic thing; no one in my household found them bitter in the slightest.)
Many people enjoy flavors in cheese they would never tolerate in other foods. Milk that smells like cheddar generally gets tossed. Blue cheese in particular smells very much like mold and earth. Even though it's a gut reaction, I think it's something to do with knowing that the cheese is supposed to smell that way, and the milk isn't. And it was interesting—once I knew the black walnut was supposed to taste like this, the flavor turned around and became very pleasant. It's somewhere between a very mild English walnut, a hint of almond, and blue cheese. No astringency to speak of. Very nice on salad. So now you're forewarned, and hopefully will be able to give it a fair shot.
That said, you're unlikely to find them in stores unless you live in the central to eastern United States, where there are hulling stations and commercial operations. English walnuts have relatively thin shells, but black walnut has a formidable shell around 5 mm thick, and this imposes a severe limit on their commercial ready-to-eat availability. You may have to find a tree, collect the fallen green fruits (avoid any with big black spots), husk, dry, and crack them yourself. It's good family fun; my daughter enjoyed picking out the bits of nutmeat after I did the cracking. It's actually quite fun, but if you have light skin you'll want gloves to keep your hands and fingernails from getting stained by the juices of the husk. (The lovely brown stain wore off my skin after about a week of normal handwashing, but the edges of my fingernails looked dirty for about a month.) Wear clothing you don't mind getting permanently stained. You'll also need a hammer or vice to open them, not a nutcracker—and perhaps eye protection.
I'm still exploring how to use them. As I said they're lovely on salad. There's a classic salad of spinach, pear, candied pecans, raspberry vinaigrette, and blue cheese. (Weird fact: This is the only way I can eat blue cheese, otherwise I rapidly get a headache.) You could probably make a pared down version of this using just spinach, pear, black walnut, and balsamic vinaigrette. I've also seen recipes for pie or ice cream. My spouse suggests they might be made into a vegan blue cheese, and I think there's some real potential there as well.