Step 1

Preheat the oven to 375℉.  Arrange the unbaked tart shells on a large baking sheet and bake for 15 minutes in the preheated oven.  While the tart shells are baking, prepare the filling:

Step 2

In a medium-size saucepan, stir the chopped rhubarb, sugar, and cornstarch until the rhubarb is coated.  Add in the water and turn the stove on to medium heat.  Cook the mixture for about 5 minutes, bringing it to a simmer, then add the chopped strawberries and cook on low for about another 5 minutes, stirring frequently.  Turn off heat and let stand until ready to fill the tart shells.

Step 3

When the tart shells are done baking after about 15 minutes in the oven, take them out and distribute the prepared filling evenly between all 18 shells.  Place the tarts back in the oven and bake for about 20 more minutes.  Let the tarts cool and serve with whipped cream. Enjoy!