Place the chopped rhubarb and water in a saucepan. Heat over medium heat, allowing it to simmer until the rhubarb is soft, approximately 5-7 minutes. Once cooked, remove from heat and let it cool.

In a blender, combine the cooled rhubarb, apple cider vinegar, and honey (or maple syrup). Blend until smooth.

Gradually add in the olive oil while blending to create an emulsion. This will give the vinaigrette a silky texture.

Add salt and pepper according to your preference. Blend again briefly to combine all the ingredients.

Pour the vinaigrette into a sealed container and store it in the refrigerator until needed. Shake well before serving.