In the bowl of an electric mixer, combine the flour, water, starter, olive oil, yeast, and salt. Mix on low speed until combined.

Scrape down the sides of the bowl to make sure all the ingredients have been incorporated.

Use the dough hook to mix on medium speed for 5 minutes until the dough is smooth, but still sticky and quite loose.

Transfer the dough to an oiled bowl and allow to rise for 1-2 hours, until puffy and almost doubled in size.

Coat the bottom of a 9×13 pan with melted butter.

Transfer the dough to the pan and spread out with your fingers until it covered the bottom.

Sprinkle half of the diced strawberries evenly over the dough.

Carefully fold each end of the dough over the strawberries so that the dough is 1/3 of the size, envelope style.

Carefully rotate the dough so that it fits the pan better again (some of the strawberries will escape, and thats ok!).

Cover the pan and allow it to rise again for another 1-2 hours,  until mostly doubled and puffy.

Preheat the oven to 425 F with the rack in the bottom third of the oven.

Sprinkle the remaining strawberries over the top of the dough, and the use your fingers to dimple the dough, pushing the berries into the dough. Move from one end of the pan to the other.

Bake for 25-30 minutes, until golden.

Allow to cool most of the way in the pan, and then remove to a wire rack. 

Dust with powdered sugar.