Preheat the oven to 350°F (175°C). In a mixing bowl, combine flour, sugar, and salt. Cut in the cold butter until the mixture resembles coarse crumbs.

Press the mixture into the bottom of a greased 9x9 inch baking pan. Bake for 15 minutes or until lightly golden.

In a separate bowl, combine chopped rhubarb, sugar, and flour. Mix well.

In another bowl, whisk together the eggs, vanilla extract, and salt. Add the rhubarb mixture and stir until combined.

Pour the filling over the baked crust and return to the oven. Bake for an additional 25 minutes or until the filling is set.

Allow to cool completely before cutting into bars.