Prepare the Filling: In a large skillet, heat olive oil over medium heat. Sauté the chopped onion until soft. Add the rice, parsley, dill, salt, pepper, and cinnamon, stirring to combine. Pour in the vegetable broth and lemon juice, then bring to a simmer. Cook until the rice is tender and the liquid is absorbed, around 15 minutes.

Roll the Dolmades: Lay a grape leaf on a flat surface, vein side up. Place a spoonful of filling at the bottom of the leaf. Fold the sides over the filling, then roll tightly from the bottom to the top. Repeat with remaining leaves and filling.

Cook the Dolmades: Place the rolled dolmades seam-side down in a large pot. Add water to cover the grape leaves and a splash of olive oil. Place a plate on top to keep them submerged, then simmer on low heat for about 45 minutes.

Make the Lemon Sauce: In a small bowl, combine lemon juice, salt, and pepper to taste. Serve the dolmades warm or at room temperature, drizzled with the tangy lemon sauce.