In a large saucepan over medium heat, add the water, honey, lemon juice, vanilla and bring to a boil. Reduce heat to low and simmer, uncovered, for 8 minutes. Add dried figs and anise, and simmer until jammy, 25 to 30 minutes.
Remove the fig mixture from the heat and cool slightly. Transfer to a food processor and blend until smooth. Transfer to refrigerator to cool completely.
While the figs are cooking, make the rhubarb syrup for the icing. In another small saucepan over medium-high heat, add the water, rhubarb, and honey. Simmer until the rhubarb turns to mush, 15 to 20 minutes. Let cool. Carefully strain and discard rhubarb pieces. Set rhubarb syrup aside.
Heat the oven to 400ºF. Line a baking sheet with parchment paper and set aside.
Lay both pieces of pastry dough on a work surface. Roll the circles to 11 inches across. Use a knife or pizza cutter to cut the edges off (about 1 inch off all sides) to create two 9-inch squares. Then cut each square into three 3-inch strips.
Spoon 1 to 2 tablespoons of the cooled jam on one end of each strip. Fold one end over the end with jam. Use a fork to crimp the edges on all sides. Repeat with remaining dough strips. Transfer the hand pies to a baking sheet lined with parchment paper.
Bake for 15 to 20 minutes, until golden. Remove from the oven and cool them completely.
Finish making the glaze: Whisk powdered sugar with 1 to 2 tablespoons of the rhubarb syrup until it creates an icing glaze. Spoon over the top of each fig pop tart and let harden. Serve warm or at room temperature.