Strawberry-Rhubarb Crisp

For the Topping:
1 cup unbleached all-purpose flour
½ cup packed light brown sugar
¾ cup old-fashioned rolled oats
2 tablespoons yellow cornmeal
2 teaspoons ground cinnamon
¼ teaspoon fine sea salt
8 tablespoons (1 stick) cold unsalted butter, cut into ½-inch cubes
1 tablespoon canola oil
For the Filling:
2 cups strawberries
4 cups 1-inch pieces peeled rhubarb
1 ¼ cups turbinado sugar
3 tablespoons unbleached all-purpose flour
1 tablespoon cornstarch

Position a rack in the lower third of the oven and preheat the oven to 350°F. Butter a 9-inch deep-dish pie plate and line a baking sheet with parchment.
To make the topping: In a medium mixing bowl, stir together the flour, brown sugar, rolled oats, cornmeal, cinnamon, salt, butter, and oil with a fork until completely blended. Set aside. To make the filling: In another medium bowl, combine the strawberries and rhubarb with the turbinado sugar, flour, and cornstarch, stirring to coat the fruit.
Pour the fruit mixture into the prepared pie plate. Sprinkle the topping evenly over the fruit mixture. Place the pie plate on the prepared baking sheet. Bake for 40 to 45 minutes, until the fruit is bubbling around the edges and the top is golden brown and crispy. Let cool slightly.
Serve the crisp warm. It is best served the same day, but it can be covered with plastic wrap and refrigerated for up to 3 days.