In a large bowl, combine all of the fruit layer ingredients (rhubarb, strawberries, sugar, lemon juice, cornstarch, vanilla extract, and lemon zest). Divide the fruit mixture between the ramekins.
2 cups fresh bright red rhubarb, 2 cups fresh strawberries, ⅓ cup granulated sugar, ½ lemon, 1 Tablespoon cornstarch, 1 teaspoon pure vanilla extract, ½ teaspoon fresh lemon zest