Pre-bake the tart shells according to the package instructions. Let them cool to room temperature

In a saucepan, place the rhubarb, strawberries, sugar and orange juice and bring to a boil over med/high heat. Once the mixture boils, turn down the heat and simmer

Combine the cornstarch and water into a slurry, and then add to the simmering rhubarb mixture. When the mixture thickens, remove from heat and let cool slightly.

Spoon the rhubarb filling into the tart shells at approximately 1 tbsp each. Let completely cool and refrigerate until ready to serve

Enjoy!