Sheep Sorrel (Rumex acetosella) A sour and attractive little leaf. You can work this leaf into a salad to add delicious acidity. It can be cooked although it disintegrates quite quickly so it is best to just add it to hot food.It also makes a fantastic sauce or dressing, a good replacement for lemons: simply put the leaves in a small blender and pack down. Add just enough boiling water to cover the leaves and blend. You can then add a little mustard, salt, garlic and black pepper and turn the blender on again. Add oil very slowly and blend until the mix has emulsified.