Strawberry Rhubarb Crisp

In a large bowl, stir together the strawberries, rhubarb, orange juice, and only ½ cup of sugar until the sugar has dissolved and become syrupy.
1 lb strawberries, quartered
1 lb rhubarb, cut into ½" pieces
1 Tbsp freshly squeezed orange juice
Empty the fruit into a colander. Set the colander over the same large bowl you used in Step 1. (This will allow the liquid that exudes from the fruit to drain.)
Allow the fruit to macerate in the sugar at room temperature for 1 hour — stirring with a rubber spatula or wooden spoon every 15 minutes — until the fruit has reduced in size and the liquid has drained into the bowl below.

Meanwhile, preheat oven to 350℉.
In the bowl of a stand mixer fitted with the paddle attachment, on low speed, mix flour, brown sugar, granulated sugar, and salt. Add in oats and continue mixing until well combined.
¾ cup all-purpose flour
1 cup oats
⅓ cup granulated sugar
⅓ cup light brown sugar, packed
¼ tsp kosher salt
Dice chilled butter into ¼" pieces and add into the mixture. Mix on low/medium speed until the mixture comes together and no dry spots remain (about 3 to 5 minutes). Note: The mixture may appear dry at first — that’s OK... just keep mixing!
8 Tbsp (1 stick) unsalted butter, chilled and cut into ¼" cubes
Using your fingers, clump the dry mixture together. Chill in the refrigerator while preparing the strawberry rhubarb filling.

After the strawberries and rhubarb have macerated for the full hour, remove the colander from the bowl and discard the liquid that has drained into the bowl. (This will also discard some of the sugar — that is okay!)
Empty the strawberries and rhubarb back into the same large bowl. Add in the remaining ½ cup of sugar, along with the orange zest, cornstarch, and salt. Mix until well combined (the mixture will be gooey).
1 tsp orange zest
¼ cup cornstarch
¼ tsp kosher salt
Add in the diced butter and mix until well distributed throughout the mixture.
2 Tbsp unsalted butter, chilled and ⅛" diced

Pour strawberry rhubarb filling into an 8" square baking dish.
Using your fingers, evenly cover the top of strawberry rhubarb filling with streusel (crumble topping).
Set the baking dish on a sheet pan. Bake in the center of the oven until filling is bubbly and crumble topping is golden brown (about 60 minutes).
Allow to cool on a wire rack for at least 1 hour before serving (otherwise liquid may seep out), or allow to cool completely and refrigerate.