To prepare filling: Put a large pot of water on to boil. Fill a large bowl with ice water. Cut an X on the bottom of each peach and tomato. Drop them into the boiling water a few at a time and cook until the skin starts to split away from the X, 15 to 30 seconds. Transfer to the ice bath. Peel and cut into 1/2-inch wedges. Combine in a large bowl with 1/4 cup each granulated sugar and brown sugar, lemon zest, lemon juice and 1/4 teaspoon salt. Let stand at room temperature for 1 to 2 hours or cover and refrigerate for up to 1 day, stirring when convenient.Advertisement
Strain the accumulated juice into a small saucepan. Boil over medium-high heat until reduced by about half, 8 to 10 minutes. Stir the syrup back into the fruit to combine.
To prepare crust: Combine flour, cornmeal, baking powder and salt in a medium bowl. Beat butter, granulated sugar, brown sugar and oil in a separate bowl with an electric mixer on medium speed until light and fluffy. Add egg and vanilla; beat until incorporated. Reduce the mixer speed to low and slowly add the flour mixture until just combined. Wrap the dough in plastic and refrigerate for at least 30 minutes or up to 2 days.
To assemble & bake cobbler: Preheat oven to 350 degrees F. Coat a 9-by-13-inch baking dish with cooking spray.
Spoon the filling into the prepared dish. Divide the crust into 12 roughly equal portions. Shape each into a 1/2-inch-thick disk. Place on top of the fruit, without overlapping but with very little exposed filling in between.
Bake the cobbler until the fruit is bubbling and the crust is golden, about 1 hour.
Make Ahead Tip: Prepare fruit (Step 1) up to 1 day ahead. Prepare crust (Step 3) up to 2 days ahead.
1 starch, 1 1/2 other carbohydrate, 1/2 vegetable, 2 fat