Cooking with invasive Japanese knotweed and garlic mustard
For a plant that is supposed to be everywhere, Japanese knotweed can be hard to find — at least in early April, and by my untrained eye.
A week ago, I set out to collect enough to cook with. But the only place I could locate knotweed mature enough to gather, curiously enough, was in the backyard of Seven Days political editor Andy Bromage. Tiny, red-tinged shoots poked up through the dried leaves there, and Andy noted they will grow like wildfire once the weather warms. “Pull up as much as you like. Just don’t drop some in your own backyard,” he quipped.
I’ve gathered and cooked with nettles, ramps, burdock, trillium and other wild edibles — but never with invasive plants such as Japanese knotweed and garlic mustard. And, since the latest strategy to fight them is eating them, I resolved to try.
Knotweed’s reputation is so sinister that you might think the plant ascended from hell. In fact, Americans brought it from Japan as an ornamental in the late 18th century. Eventually, it went haywire, taking over moist and disturbed areas with verve. Knotweed can grow so thick that it chokes riverbanks and crowds out other plants. Its powerful rhizomes send up bamboo-like shoots that can grow three to four inches a day and reach heights of seven feet or more.
Because Japanese knotweed has only a short edible period — its stalks can become tough in a matter of days — I thought early spring would be the perfect time to pick it at its most tender. So I canvassed marshes, riverbanks, the sides of railroad tracks. But mostly I stumbled across last year’s stalks, or plants too tiny to bother with. (Lesson No. 1: Next time, tag along with an experienced wildcrafter.)
Still, I managed to gather enough for one meal. When digging the stuff up, it’s important to pull out the root, which will vigorously regenerate if left in the ground. To do this, I used a knife to saw a little circle around each baby plant before uprooting it.
Garlic mustard was another matter. Once I knew what it looked like — thanks to Jon Kart — I began seeing it everywhere.
Kart is a biologist with the Vermont Fish and Wildlife Department. This year he’ll be leading the Great Richmond Root-Out , an ongoing effort to restore and maintain Richmond’s silver-maple-ostrich-fern flood plain forest.
When I called Kart, he was in Burlington for a meeting. “You can see some right here, growing along Battery Street,” he told me. I went straight over, and there it was, along the park’s edge: rosettes of green, vaguely heart-shaped leaves growing close to the ground.
Kart said the taste of garlic mustard varies with location, and he took a bite. “It’s more bitter than usual here,” he observed. I agreed that the leaves had a sharp finish.
Kart also pointed out the root’s slight kink, a survival strategy to ward against uprooting.
Garlic mustard, a biennial, was brought to the states from its native Europe by colonists who kept it as a potted herb. Once it jumped its bounds, the plant spread far and wide, monopolizing soil nutrients, water and space, and crowding out native species.
Because garlic mustard stays green all winter, it’s easy to recognize now. I gathered a few pounds from various roadside banks, being careful to pull up the kinked roots.
Next, I called chef and author Didi Emmons for culinary advice. Emmons’ new book, Wild Flavors: One Chef’s Transformative Year Cooking From Eva’s Farm  (Chelsea Green Publishing), collects recipes and tips from the garden of Eva Sommaripa, a Massachusetts farmer who supplies many northeastern chefs with unusual herbs and edibles.
Emmons says she doesn’t care much for the flavors of garlic mustard but has seen knotweed put to many creative uses, such as an “invasive sorbet” of Sommaripa’s. Because of its sour notes, knotweed is often paired with sweet flavors; Emmons first tasted it in a strawberry-knotweed pie. But she prefers it in savory dishes.
“The flavor is lemony, but a very mild lemony, something between celery and a potato,” she observes. “I think the best application is cooking it like a vegetable, such as [in] a pasta with thyme, chard, Parmesan and maybe a cream sauce. It’s important not to overcook it. Its texture is crunchy, and that’s part of its pleasure.”
Back in my kitchen, I chewed on a knotweed leaf before deciding on a dish. To me, it tasted like an earthy, pungent green with a racy backbone. I decided to use it in a pasta, too, paired with some pork sausage and garlic.
The garlic mustard — its flavor is like watered-down garlic — was versatile. I tossed some in a green salad that I topped with a poached egg, and buzzed together a chimichurri sauce that I slathered over grilled skirt steak. I came across a recipe for knotweed-infused vodka that I plan to try when the plant gets large enough.
Someone in the office suggested I hunt down some zebra mussels and Eurasian milfoil, too. Stay tuned.
I used the young stalks and greens of knotweed as a substitute for broccoli rabe in one of my favorite pasta dishes. Any pasta will do.
Put a medium saucepan on to boil and heavily salt the water.
Peel garlic and slice thin. Rinse and dry knotweed and ramps.
For both the knotweed and the ramps, separate the stalks from the stems; coarsely slice the stalks into approximately ¼-inch slices, and coarsely chop the leaves.
Squeeze the sausage meat from the casings into a small bowl.
Once water is near a boil, put a steep-sided sauté pan on medium heat; when it is hot, add olive oil. Add pasta to water and stir. Add garlic to pan and swirl in oil for 30 seconds. Add sausage meat to pan and cook until brown, about three to four minutes. Add stalks and sauté for two minutes; add knotweed, ramp greens and oregano and turn heat to very low.
Drain pasta, reserving about a half cup of the cooking water. Add pasta to sauté pan, sprinkle on crushed red pepper, add two tablespoons of reserved liquid and stir until blended. Remove from heat and top with grated Parmesan. Add salt and pepper to taste, and serve.
I haven’t yet tried this, as knotweed is still too tiny. But I plan to.
Recipe courtesy of Andy Hamilton, author of the forthcoming book Booze for Free .
Gather knotweed shoots and chop into 1-inch pieces, then put in a 1-liter jar. Add the sugar and vodka and seal. Shake well and leave for at least three to four weeks. Strain back into bottle through muslin or cheesecloth and place in a cool, dark place for three months.
Chimichurri is a classic Argentiné sauce made with green herbs. Garlic mustard’s flavor is subtle, so I included some actual garlic, too, along with parsley, chives and oregano. You can experiment with any combination of green herbs — basil or cilantro, for example. Be sure to get a good char on the steak, as this sauce needs to play against some smoky flavors.
Separate garlic-mustard leaves from the roots and stalks and discard them in a plastic bag, not the compost bin (where they might root and spread). Rinse leaves and spin or pat dry.
Smash garlic cloves with the back of a knife and peel. In a food processor, pulse garlic and shallot for a few seconds. Add garlic-mustard leaves, parsley, oregano, chives and pepper, and pulse until shredded. Pulse in oil, vinegar and lime juice until mixture forms a paste. (Alternatively, finely mince the herbs and garlic by hand and combine with the liquids.) Add salt to taste.
Salt and pepper both sides of the skirt steak and marinate with ? of the sauce. Refrigerate for at least two hours, while letting the remaining sauce sit at room temperature. Bring the steak back to room temperature before grilling.
Heat a grill until very hot and sear steak on both sides. Turn down heat and cook to desired doneness. Spoon sauce over and serve.
I love very simple salads — fresh greens dressed with a tangy vinaigrette. When served with a poached farm egg and grilled bread, they can become an entire meal. Throw in whatever greens you like — I used baby kale and ramp greens as well as garlic mustard. I strongly urge you to seek out some blueberry balsamic vinegar, as it’s sublime.
Crush garlic with the handle of a large knife and peel. Place garlic in a small bowl; add some sea salt and ¼ teaspoon olive oil. With a pestle or the blunt handle of a wooden spoon, mash garlic, salt and olive oil together.
Rinse all greens and spin or pat dry. Squeeze together small bunches and slice thinly. Add to a large bowl.
Add vinegar to mashed garlic and stir. Slowly drizzle in remaining olive oil, whisking until emulsified. Add salt and pepper to taste. Drizzle over greens and toss well. Let salad sit for at least a half hour to soften the greens. Divide the salad into two bowls.
Put a small saucepan of water on to boil.
Over medium heat, melt butter in a skillet until bubbling. Add bread and toast on both sides.
Once water is boiling, poach the eggs. Carefully slide an egg onto each bowl of salad. Add grilled slices of bread to the side of the salad, crack some black pepper on top and serve.