Sunday, April 13, 2008

Sour Tastes for Locavores

Oxalis oregana is a sweet (and sour) little Northwest native.

Northwesterners aspiring to a foodshed diet may pine for the taste of sour. If you pass by the grocery displays of lemons and limes and don’t fancy swigging local vinegar, what’s left? Some people seem born with a craving for sour tastes. One of my daughters would suck on a lemon slice in preference to scarfing a brownie, to my chocoholic amazement. Years later when we met some of her birthrelatives, we learned that a slice of lemon was also her great-grandmother’s standard treat.

Recent taste studies involving identical twins indicate that the neural receptors for sour tastes do in fact vary markedly with family genetics. People who have fewer receptors for this flavor tend to crave more sour; folks with an abundant supply are quicker to reach overkill. Maybe they are the ones who keep the sweet pickle manufacturers in business.

Sour tastes and hot weather seem to be a natural pairing, and hot-climate cuisines have developed a wider array of flavorings than we commonly see in the Pacific Northwest. Amchoor, the powdered green mango popular in Indian cuisines, is one astringent example. Tamarind, common to both Asian and traditional Mexican cooking, is another.

If you want homegrown sourness, here are some possibilities.

Local nurseries carry Meyer lemons and other dwarf citruses. The Meyers are generally considered the easiest and hardiest for Northwest gardeners. I’ve had mine for a decade and it’s been outside into the high 20s a few times. When it’s indoors for the winter its glossy foliage and waxy, heavily sweet-scented flowers are an extra holiday treat. This year I used it as my Christmas tree. Having said all that in its favor, I have to admit mine has produced very few actual lemons--the real point of the quest for sour--in the past few years. I think a repotting is in order.

Sumac—The small berries of the staghorn sumac yield a flavor that is better known in the Middle East than here. In Europe it was a well-known souring agent before the importation of citrus fruits. It’s a nice, fresh taste, tart but not bitter, and when used for herb tea or “lemonade” it makes a lovely pink. Sumac powder, either plain or mixed with thyme and sesame--the spice combo known as zataar--is sold at the Mediterranean Deli behind Sehome Cinema. It is used in lamb dishes, including the eponymous Iranian soup ash e-somaq.

If you want to grow your own, sumacs are beautiful little trees with velvety branches and flamboyant fall color, but be forewarned that they spread very aggressively. Be prepared for constant vigilance if you don’t want your specimen to turn into a grove.

There are at least two genuses called sorrel, the culinary variety Rumex and the multiple wild and ornamental types--Oxalis. All taste fresh and sour, and all are edible, although the Rumex varieties are the only ones generally used in cooking. French sorrel is a hardy perennial that sends up its blade-shaped light green leaves in early spring. Like its pestiferous cousin, dock, it is a chore to dig up once established and it lives for years, so choose its spot carefully. Oxalis plants are the various ground-covering creepers with clover-like leaves and delicate flowers, usually white but sometimes yellow. I like to grab a few leaves while hiking. Their bright taste is as good as a rest stop, almost.

A good introduction to cooking with sorrel is Green Soup, which has so many versions it is more a technique than a recipe. Serious locavores and vegans can easily adapt this recipe to their needs (skip the nutmeg, use soy milk, etc.). Coconut milk might be a tasty variation, moving toward a Southeast Asian flavor combo.

3 tablespoons butter
half a medium onion, chopped
2 medium potatoes, peeled and diced
1 quart chicken stock
salt and pepper
2 cups fresh sorrel leaves or a combination of tender greens
2 tablespoons dry sherry (optional)
1/2 cup light cream
freshly grated nutmeg (optional)
chopped parsley
chopped chives

Melt butter in a heavy saucepan and cook onion until soft but not brown.

Add potatoes and cover with stock. Season with salt and pepper and simmer until potatoes are tender, about 15 minutes.

Pour a cup of soup and a handful of greens into the blender and purée at high speed. Repeat until all the soup and greens are blended. The mixture should be a nice fresh green.

Return mixture to saucepan, add sherry (if used) and reheat. Add a little more stock or water if the soup is very thick. Stir in cream, heat, and correct seasoning.

Add several grinds of fresh nutmeg (if used). Serve hot, garnished with parsley and chives.

Serves 6.

People who only use rhubarb for pies are missing out. Just as a squeeze of lemon improves just about any seafood, a simple rhubarb sauce is a great foil for fish. It’s also a beautiful garden plant. I don’t know if I’ve ever actually bought any at the store. As with zucchini, there always seems to be a neighborhood surplus.

2 cups rhubarb, chopped
1/3 cup tomato paste
3 tablespoons olive oil
sugar to taste (from none to 3 tablespoons)
1/2 cup water

Put these together in a medium saucepan, bring to a low boil, and then reduce to simmer. Cook until rhubarb is tender and serve over baked or broiled fish.

A health note
Citrus gets its sourness from citric acid. The various sorrels and rhubarb get theirs from oxalic acid. Nutritionists warn against overloading on oxalic acid because it interferes with the uptake of important dietary minerals, especially calcium. A general rule of using these plants for flavoring and treats rather than as a dietary staple will keep diners out of trouble.

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