Summer Tomato, Herb, and Bacon Pie

Line a baking sheet with two layers of paper towels. Cut the stem ends off the tomatoes, then gently squeeze out as many seeds as possible. Slice the tomatoes to a thickness of ¼ inch. Place the tomatoes on top of the paper towels in a single layer and sprinkle with salt. Layer more paper towels on top of the tomato slices and repeat with remaining tomatoes. Let sit at room temperature for at least one hour or up to five hours.

Preheat the oven to 350 degrees. Cook the bacon over medium heat in a large skillet for about 8 minutes, or until crisp. Using a slotted spoon, remove the bacon and place it on a paper towel-lined plate. Remove all but 1 tablespoon of the bacon fat from the skillet.

In the same skillet over medium-low heat, season the onion with a little salt and cook for about 30 minutes, stirring occasionally, until it is soft and caramelized. 

Beat the egg in a small bowl, then stir in the mayonnaise and dry mustard. Once combined, stir in the cheddar, parmesan, and fontina. 

Line the bottom of the pie crust with 1/3 of the tomatoes, then season them with salt and pepper. Top with half the onions, then half the bacon, then half the chopped herbs. Spread half the egg-cheese mixture over. Repeat with another 1/3 of the tomatoes and the remaining onions, bacon, herbs, and cheese (reserve about a tablespoon of the herbs for garnish). Top the pie with a single layer of sliced tomatoes. 

Bake the pie for 40 minutes, or until the top begins to brown and bubble. Let it sit for at least 10 minutes before serving. Serve warm, at room temperature, or cold, sprinkled with some of the chopped herbs.