Mix the oatmeal with the water in a bowl.
Leave aside for 15 minutes until it absorbs all the water.
Cut and discard the thick stalks of parsley.
Wash and dry all the herbs well and chop them finely with a sharp knife or in a blender. (if you use a multimixer don't leave them too long).
Put the oatmeal, parsley, basil, tomatoes, lemon and oil in a salad bowl and mix well.
Put them in the fridge for at least 1 hour.