Sweet strawberries and tart rhubarb baked under a golden, tender biscuit-style topping in a cast iron skillet. The cast iron gives you lightly crisp edges while keeping the center soft, and everything bakes in about 30 minutes.
Toss the sliced strawberries and rhubarb with sugar, cornstarch, lemon juice, vanilla extract, lemon zest, and salt in a large bowl. Stir gently until everything is evenly coated.
Transfer the fruit mixture to a 10-inch cast iron skillet and spread into an even layer.
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and lemon zest. In a separate bowl, stir together the melted butter, milk, vanilla extract, and remaining sugar. Pour the wet ingredients into the dry and stir just until combined. Do not overmix.
Spoon the batter over the fruit in large dollops, leaving gaps so the fruit can bubble through during baking. Sprinkle turbinado sugar evenly over the top.
Bake at 375°F for 30 to 35 minutes until the topping is golden brown and the fruit filling is bubbling around the edges.
Remove from the oven and let cool for 10 to 15 minutes. Serve warm with a scoop of vanilla ice cream.
Notes
Don't overmix the batter. Overmixing develops gluten, which makes the topping dense and chewy instead of soft and tender. Stir until the dry ingredients are just incorporated. A few small lumps are perfectly fine.
Leave gaps in the topping. Dollop the batter in spoonfuls rather than spreading it edge to edge. The fruit bubbles up through the gaps as it bakes, which is the hallmark of a good cobbler.
Use a baking sheet underneath. Fruit juices can bubble over, especially with juicy strawberries. A sheet pan catches drips and saves your oven from a sticky mess.
Wait before you serve. 10-15 minutes of resting lets the cornstarch finish setting up. If you dig in immediately, the filling will be loose and runny.
Watch the edges, not the center. The cobbler is done when the fruit is actively bubbling around the edges and the topping is golden brown. A toothpick in the center of the thickest biscuit section should come out clean.
Adjust sugar to your rhubarb. Rhubarb tartness varies widely by season and variety. Taste a piece raw before mixing. If it makes you pucker hard, add 1-2 extra tablespoons of sugar to the filling.