Our Thanksgiving table will include  root vegetables like Yukon Gold potatoes, sweet potatoes, onions, beets, parsnips and carrots. Even the Pilgrims might have had some of these vegetables at the first Thanksgiving. Root vegetables were an important part of the food supply in Europe before canning and freezing were available. Root vegetables were harvested in the fall and stored for winter use without preserving them in some way, like pickling or drying. When I was a child living…