In a large bowl, whisk together the flour, cornmeal, baking soda, and baking powder.
In the bowl of a stand mixer fitted with the paddle, beat the butter, sugar, corn powder, and salt on medium-high speed until creamy and fluffy, about 1 minute. Beat in the egg, sour cream, and vanilla. Add the flour mixture all at once and beat on lowest speed until just combined.
Crumble a layer of dough into a medium bowl. Top with a couple spoonfuls of roasted strawberries, spreading out to create ripples. Repeat until you've layered all the batter and strawberries into the bowl. The bottom and top layer should be dough (see Note 2).
Once all the dough and strawberries have been layered in the bowl, gently press down the layers to create an even surface.
Using a 3-tablespoon scoop, scoop the dough onto a parchment-lined sheet pan or a couple dinner plates. Cover with plastic wrap and refrigerate for at least 2 hours and up to overnight.