Preheat the oven to 400°F.
In a small bowl, whisk together the mayonnaise and lemon juice; set aside.
In a non-stick skillet over medium heat, cook the bacon until desired doneness. Transfer the bacon to a paper towel-lined plate to drain and crumble into bite-size pieces. Pour off bacon fat, reserving 1 tablespoon in the skillet. Heat the skillet over medium-high heat. Add the onion and sauté until soft and translucent, about 5-7 minutes. Add the garlic and sauté until fragrant, about 1 minute. Transfer the onion mixture to a large bowl and allow to cool.
Add the crumbled bacon, corn, basil, chives, remaining ½ teaspoon salt, peppers, cheeses, and cornstarch to the cooled onion mixture; tossing until thoroughly combined.
Place half of the cheese mixture in the crust. Arrange half of the tomatoes on top. Repeat with the remaining cheese mixture and tomatoes.
Pour lemon mayonnaise over the filling.
Roll out remaining piece of dough on a floured work surface in a 12-inch round. Fit over filling, folding overhang under the edge of the bottom crust and pinching to seal.
Cut several steam vents in top of crust and brush with the egg wash.
Bake until the crust is golden and the filling is bubbling, 30-35 minutes. Cool on a rack and serve warm or at room temperature. (Pie can be baked 1 day ahead and chilled. Reheat in a 350°F oven until warm, about 30 minutes.) Enjoy!