Combine the rhubarb, water and sugar in a small pot. Heat over medium heat. The sugar will melt and the rhubarb will start to get soft.
Once the water comes to a low boil and the rhubarb is soft when you press a spoon into, remove from the heat and mix in the lemon juice.
Use your emulsion blender to blend the sauce into a uniform texture. Alternatively you can transfer the sauce into a blender and blend it all together. Let cool before serving!
Video
Notes
RECIPE TIP: You can freeze rhubarb sauce. Make sure whatever container you use to freeze the sauce in has a little extra space for the sauce to expand.