First pick enough watercress for the 75 grams of leaves. The stems you can keep for another recipe.
Then season a pan of boiling water with salt and blanch the leaves for 30 seconds. Directly cool them down in ice water to prevent them from turning brown.
After a minute squeeze all the water out of the leaves. Transfer the leaves into a blender and also add the vegetable broth, the apple cider vinegar, the salt and a knife tip of xanthan gum. Blend it till smooth.
Then pour it into a bowl and cool it in your fridge so it keeps its beautiful bright color.