Wash the rhubarb stalks thoroughly and chop them into 1-inch pieces.

Place the rhubarb pieces and the split vanilla bean into a large, sterilized glass jar.

Pour the vodka over the rhubarb, ensuring all pieces are completely submerged. Seal the jar tightly.

Store the jar in a cool, dark place for 3 to 4 weeks, shaking it gently every few days to help extraction.

After the infusion period, prepare a simple syrup by combining sugar and water in a small saucepan; bring to a boil until sugar is dissolved, then let it cool completely.

Strain the rhubarb-infused vodka through a fine-mesh sieve or cheesecloth into a clean bowl or bottle, discarding the solids.

Stir the cooled simple syrup into the infused vodka. Seal and let it rest for at least one more week for the flavors to mellow before serving.