Sorrel-Onion Tart

If you enjoy the lemony flavor of sorrel, this tart is a real treat. It is another sorrel recipe from Deborah Madison's The Greens Cookbook; I recently posted her recipe for Potato-Sorrel soup, which you can find here. I am a great fan of sorrel; not only is it an easy to grow perennial herb, it is delicious in soup cold and hot, and in this tart. For those of you who don't like to make pie crusts, I suppose you could use a ready-made shell. This recipe is for a 9 inch tart or pie; it may look complicated, but it really is quite simple.

Tart Dough
1 cup flour
3/8 teas salt
4 Tbs cold unsalted butter, cut into small cubes
1 1/2 Tbs solid vegetable shortening
3 Tbs ice water

1. Combine flour and salt in a bowl, then add butter and shortening. Cut flour and fat together with fingers, knives, or old-fashioned kitchen tool, which is what I use.
2. Add cold water, gently tossing with fingers, adding a bit more if needed to hold dough together. Gather into a ball, flatten into a disk and cover with waxed paper. Let rest in refrigerator for 1/2 hour.
3. Roll dough and place in pan, leaving an inch overlap; fold it under, leaving dough 1/4 inch or so above the edge of the tart pan.
4. Partially pre-bake the crust by first freezing the empty shell till firm, then baking in a 425 degree oven for 8 to 10 minutes till just beginning to color.

The Tart filling
4 Tbs butter
1 large red onion (I didn't have a red onion, so used yellow; I think red is for pretty color)
1/2 teas salt
4 to 8 ounces sorrel, stems removed and roughly chopped (I use a lot because I like the flavor of the herb; if you don't want such an insistent flavor, use less.)
2 large eggs
1 cup heavy cream (Not wanting such a rich tart, I use low fat milk)
2 ounces Gruyere cheese, grated (being in Vermont, I use sharp cheddar)
pepper

1. Melt 3 Tbs butter in a wide pan. Add onion and salt; cover and stew slowly till onion is very soft.
2. Melt remaining tablespoon of butter and add the sorrel by large handfuls; it will cook down to nearly nothing after 3 or 4 minutes.
3. Whisk eggs with cream, then stir in onion sorrel mixture and half the cheese. Taste for salt and add freshly ground pepper.
4. Preheat oven to 375 degrees.
5. Scatter remaining cheese over the crust, then pour the filling on top.
6. Bake until custard is set and well colored, about 35 to 40 minutes.