Using a food processor, combine the powdered sugar, flour, butter, and half of the lemon zest. Blend just until the mixture forms a ball.
Press the dough into the sides and bottom of the tart pan. Pat to make the crust even.
Bake the crust until it is just starting to lightly brown, approximately 10 minutes. Remove from oven and set aside to cool.
Make the filling by adding the cream cheese, sugar, vanilla, and remaining lemon zest in a small bowl. Beat until smooth with a spatula. If the cream cheese is soft, this will be easy to incorporate. If the cream cheese is too stiff, microwave for 15 seconds at a time until soft enough.
When the crust is cooled, spoon the cream cheese mixture into the tart shell and spread out evenly. It is important that the crust is cool so that the filling does not melt from the heat.
Decorate the tart by first filling in the blueberries in the top left corner. Either lay them in clean rows or just pile them all in. Use more or less blueberries as desired and needed.
Remove the tops of the strawberries and slice. Starting at the top, lay the strawberry slices, slightly overlapping, across the space. Leave a gap and repeat rows of sliced strawberries. The number of rows will vary with how wide the strawberries are.