In a medium sauce pan, simmer the rhubarb with a 1/4 cup of water until the rhubarb is soft, about 12-15 minutes
Blend the rhubarb into a fine puree with a food processor or blender
Return the rhubarb puree to the sauce pan with the sugar and eggs and cook over medium low heat, stirring constantly, until the curd thickens and reaches an internal temp of 170F
Add the butter and whisk to emmulsify and then strain through a mesh sieve and cool