Last week, frost hit Walla Walla. For most of us this means little more than a few additions to our wardrobe and turning the thermostat up at night.  For the farms around Walla Walla it means a major shift in crops and harvest.  During the day, plants and soil soak up heat from the sun.  Once the sun sets they lose that stored heat.  If there are clouds in the sky, the clouds act as an insulating layer to protect the plants.  On cloudless, and especially windless, nights the temperature may drop below freezing, stored heat quickly escapes, and plants freeze.  When leaf temperatures drop below freezing point, plants are not necessarily damaged.  However, once frost crystals form they can pierce and damage the leaves.  Tomatoes and other tender plants like lettuces die when they are exposed to frost.  Hardier plants (think roots crops like carrots, beets, and turnips or thick leafy greens like kale, spinach, and cabbage) can tolerate these low temperatures and actually thrive in cool weather.

In colder temperatures and with fewer hours of sunlight these plants do not grow as fast, but they begin to take on new flavors.  After exposure to freezing temperatures, a plant’s cell structure is loosened and some of the plant’s starch is converted into sugar.  As a survival mechanism against frost, leafy greens pump sugar into their leaves to lower the temperature at which they freeze.  This means if the greens are harvested after a frost, they taste much sweeter.  The same is true for corn, winter squash, and other fall crops.   So start shifting your purchases at the grocery store or farmer’s market (it ends in just a few weeks, by the way).  Welcome in the frost with some sweet leafy greens.  Here’s an easy kale recipe to get those of you intimidated by leafy greens enthused.  Kale is high in iron, calcium, vitamin C, and beta carotene, and adds an extra oomph to stir fries, soups, scrambled eggs, and mashed potatoes.  Cut the leaves and steam or boil them for about ten minutes or until tender and bright green or sauté them like the following recipe.
 
Sautéed Kale
1       tablespoon olive oil
1/2       teaspoons red chili flakes
1       medium-sized Walla Walla sweet onion, chopped into long slivers
3       cloves garlic, chopped
1       bunch   kale, bottom part of stems removed and leaves chopped 
salt and pepper to taste

spice it up with:
1-2       teaspoons red wine or balsamic vinegar,
1       teaspoons mustard like dijon or spicy honey

Heat up the oil over medium high in a large skillet.  When the oil is hot, add the chili flakes until they start to sizzle.  Turn the heat down to medium and throw in the onion and cook for about 6 minutes or until the onions turn translucent and begin to caramelize. You may need to add more oil or a splash of water so that the onions don’t burn or stick to the pan.

When the onions are soft, raise the heat back to medium-high. Add the garlic and kale and stir. This may look like a lot of kale, but it will wilt down. Put a lid over the pan so that the kale will steam and cook  After a few minutes, take the lid off and continue to cook the kale down until tender, about 5-10 more minutes. If you want, add vinegar and/or mustard toward the end as well as salt and pepper. Enjoy your kale alone, over rice, or with a fried egg on top.