Chop crackers in food processor until smooth crumbs. Add in the brown sugar and pulse until combined. Pour the crumbs into a large bowl. Melt the butter in the microwave. Add the butter to the crumbs and mix until combined well.
Use clean hands to press the crust into a pre-buttered long rectangular tart pan. Place this in the freezer while you make the curd.
Orange + Berry Curd
Wash all the fruits, and then place the berries in the food processor and puree. Strain this mixture into a strainer placed above a saucepan. Push down on the strainer with a spoon to make sure you get all the juices. This may take some time. Next squeeze the juice from all the oranges through the strainer as well.
Add the sugar, cornstarch, and egg yolks into the saucepan. On medium heat, whisk until thickened. Turn the stove off and add butter 1 cube at a time. Continue mixing until melted. Let cool to room temperature, then cover with plastic wrap and place in the refrigerator 1-2 hours.
When ready, remove curd form the refrigerator and spread evenly into the tart. Bake at 350ºF for 20-25 mins. It will still be somewhat jiggly in the middle. Refrigerate 24 hours.
Wash, clean, and slice oranges thinly. Split the water, sugar, and corn syrup between two deep skillets, and bring to a boil. Now lower the temperature to a simmer. Add the orange slices to the skillets, not overlapping. Simmer 1.5-2 hours.
Remove slices from skillet onto a cooling rack and allow them to dry 1-2 days. Top your tart with the candied slices.
This is a make ahead dessert, as you need at least 24 hours to chill the tart in the refrigerator after it is baked, and (at the same time) 24 hours to dry the candied orange slices before decorating the tart. Please plan accordingly.
If you don't have graham crackers, it's ok to use other cookies. I've used Speculoos (cookie butter cookies) mixed with some graham crackers, and it was great!
If you have extra candied slices, you can enjoy them as a snack/dessert on their own.