Wash the rhubarb thoroughly under cold running water to remove any dirt. Remove and discard the leaves completely—they contain oxalic acid and are not safe to eat. Slice the stalks into 1-inch pieces, which ensures even cooking and breakdown.

Place the sliced rhubarb and water in a medium saucepan over medium-high heat. Bring to a boil, then reduce the heat to medium-low and simmer for about 8-10 minutes, stirring occasionally. The rhubarb will begin to break down and release its natural juices, softening significantly.

Stir in the sweetener thoroughly, making sure it dissolves completely into the rhubarb mixture. Continue simmering for another 10-15 minutes, stirring occasionally. The compote will thicken slightly as it reduces.

Remove the pan from heat. Using a potato masher or the back of a spoon, press and mash the rhubarb pieces against the sides of the pot until you reach your desired consistency. Stir in the vanilla extract, then let the compote cool slightly before serving or storing.