-
Pre-heat the oven to 425ºF. Let the pastry sit out on the counter for 5 minutes just to soften ever so slightly.
-
Roll the pastry into a large circle, about 10 to 11 inches in diameter and about ¼-inch thick. Transfer the circle to a cookie sheet lined with parchment paper.
-
Toss the rhubarb, strawberries and lemon zest together in a bowl. Add the sugar and cornstarch and toss right before placing the fruit on the pastry.
-
Place the fruit in the middle of the pastry circle, leaving a border around the edge of the circle of about 2 to 3 inches bare. Fold the edges of the pastry up around the fruit, pinching the pastry together so that it stays in place. The center of the fruit should still be exposed.
-
Brush the edge of the pastry with the melted butter and drizzle any remaining butter on the fruit in the center. Sprinkle a little sugar on the pastry and transfer the tart to the oven.
-
Bake at 425ºF for about 45 minutes, or until the pastry is nicely browned and the fruit in the center is bubbling.
-
Remove, cool and serve with some whipped cream.