2 medium yellow onions, chopped
2 tablespoons extra-virgin olive oil or clarified butter
1 1/2 pounds / 24 oz small tomatoes (here it's a mix of heirloom cherry & early girls)
scant 1/2 teaspoon fine grain sea salt
2 teaspoons balsamic vinegar
a bit of flour
zest of one lemon
1 pie crust, this rye crust is my go-to
1 egg whisked with a tablespoon of water
Preheat the oven to 400F / 205C.
While the oven is warming, uses a large skillet over medium heat to saute the onions and a couple pinches of salt in the oil/clarified butter. Cook, stirring regularly, until the onions are deeply golden and caramelized, 10-15 minutes. Remove from heat.
While the onions are cooking, cut any larger early girl tomatoes in half. I typically leave the small cherry tomatoes whole. Add to the caramelized onions along with the sea salt and balsamic vinegar. Transfer to a 10 or 11-inch cast iron skillet or equivalent deep pie dish. If you get the sense that your tomatoes are quite juicy, and might release a lot of liquid, you can toss the mixture with a tablespoon or two of flour at this point. Sprinkle mixture with lemon zest.
Roll out your pie dough, and use it to cover the tomato mixture - tucking in the sides a bit. Brush the crust with the egg wash, cut a few decorative slits in the crust, and bake in the top third of the oven until the crust is deeply golden and the tomatoes are bubbling a bit at the sides, 25 - 30 minutes.
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