Sunday, May 16, 2010

Mycorrhizal Symbiosis

One of the most prized edible mushrooms is boletus edulis, also known as porcini or cep. This mushroom has a mutualistic relationship with the trees that it grows near, especially spruce, pine, and fir trees. Biologists call this relationship mycorrhizal symbiosis, which means that both the tree and the fungus benefit from the relationship. The mushroom absorbs sugars and carbohydrates from the tree roots in exchange for the mineral salts, nitrogen and water absorbed by the mushroom from the environment.

I've always liked using natural pairs in a dish. In the spring, evergreen trees like fir and pine send out fresh growth from the tips of their branches. These tips do not yet contain the resins that would make them bitter, but instead they have a subtle sweet, grassy forest flavor. They can be used to infuse alcohols, or make a simple sweet tea called "branch water." It's flavor can also be extracted into essential oils or infused in vinegars or creams, and used as a culinary ingredient.
For several years, I have been pairing fir tips (I have several Douglas Firs in my yard) with porcini. This year, the dish is composed with a fir tip custard surrounded by a salad of grilled porcini, toasted pine nuts, blanched celery hearts and leaves, and a frothy vinaigrette made of mushroom stock and fir infused white wine vinegar. How often can you taste a mycorrhizal pairing?

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