Instructions

Pulse the flour, sugar, and salt to combine. Add the cubed butter and pulse a few more times until you get pea-size crumbs. Add the ice water and process for 5 seconds, just until the dough comes together. Do not over process.

Remove the dough from the food processor and place it on a lightly floured surface. Barely kneading, gather the dough into a smooth ball, and then flatten it into a 3/4 inch thick disk. Wrap it in a plastic wrap and refrigerate for 2 hours.

Mix the rhubarb, strawberries, with 1/3 cups of sugar, salt, and corn starch to get them fully covered. Place the mixture in the center of the dough and then evenly spread, leaving a 2-inch border around the edges. Fold the edge of the dough up over the filling to create a 2-inch border. Bruch the border with the lightly beaten egg. Generously sprinkle the border and filling with more sugar.

Bake until crust is golden and filling is bubbling 45 to 50 minutes. Let cool at room temperature. Serve warm or cold.