Wash and slice the rhubarb into small pieces, then place them in a saucepan. Add water to cover the bottom and bring to a boil.

Reduce heat to low, cover, and simmer for 8–10 minutes until the rhubarb is soft.

Blend the cooked rhubarb until smooth, then return it to the saucepan.

In a mixing bowl, whisk together the sugar, eggs, and salt until smooth. Gradually stir in the rhubarb puree.

Cook the mixture over medium heat while stirring constantly until it thickens, about 8–10 minutes.

Remove from heat and stir in butter and vanilla until melted and smooth.

Let it cool for 10–15 minutes, optionally strain for a smoother texture.

Transfer to a jar, cover, and refrigerate for at least 3–4 hours before serving.