I first took note of a prickly ash (zanthoxylum americanum) tree last spring when I noticed the cluster of green berries had a very enticing aroma. I had to find out what this bushy plant was before I tasted it, and when I identified it I learned it is not only edible, but a common ingredient in Chinese cuisine known as Szechwan pepper. Assuming the berries had to ripen before harvesting, I only recently got around to collecting a few and was keen to try cooking with them. What I didn’t realize was that the berries can be harvested any time there are leaves present, i.e. from mid-spring to late fall, so green, red, dark blue or black, they are all good.
First, a little about this tree or shrub. It grows mostly in shaded woods throughout much of central and north-eastern North America. There are closely related species elsewhere, such as the zanthoxylum bungeanum which is the one used in China and which has a similar taste. The plant can grow anywhere from 9 to 18 feet in height, and is usually part of a larger thicket.
It is belongs to the rutaceae (rue), or citrus family, which explains the lemony scent of the leaves. To help identify it, watch for these characteristics:
- a smooth grey to brown bark dotted with small mounds with a couple of spikes on each
- alternate compound leaves (5-11 on each) with a lemon scent and oval in shape
- clusters of berries growing close to the branches, green in the spring, red in the summer and blue then black in the fall. When the seeds drop out the open husks remain
- one or two hard, smooth black seeds inside the berries
A few of the berries I picked were still red, most were black, and many husks had lost their seeds but can be collected all the same.
I tasted some of the berries right off the tree. I was surprised by the flavour and the effect of eating them raw. A mixture of lemon and pepper was at first pleasant, followed by a numbing of lips and tongue – and I now understand why one of the many medicinal uses of this is for ‘dry mouth’. I found the experience slightly alarming, but hoped that roasting and/or cooking would eliminate the unpleasant effect but not the flavour.
For my first experiment, I decided to just grind one teaspoon of the berries coarsely and then roast them lightly in a skillet. I decided to pair them with nothing stronger than olive oil and crushed garlic, all of which I mixed together into a paste. I then applied a liberal coating to about one pound of chicken breast and roasted it. The flavour was as expected – citrussy and peppery and none of the anaesthetic or salivating effects were felt. I could have used a smaller amount and the flavour would still have been enough, but you will have to experiment a little yourself to find the right proportions for your palate. I believe with the addition of other spices, like cumin, ginger root, anise or chilis, a delicious ‘masala’ could be achieved.
I also roasted and ground some (a very small amount) and mixed it with ground dried garlic to season vegetables to be roasted. This method gave a very subtle flavour, a welcome alternative to black pepper (which does not grow in my backyard). With enough berries to keep me going for the winter, I will work on different spice mixtures using this newly discovered spice, and come spring I will be sure to start gathering them much earlier.
One word of caution though. These shrubs or trees are as the name suggests – very prickly. They are not difficult to pick and you can collect several in your hand at a time just be clutching a bunch, but dress to protect yourself from the thorns.