In a large bowl, add the coucous with salted boiling water. Cover and let it expand for 5 to 10 minutes, then set aside in the refrigerator for 30 minutes, stirring regularly. (The couscous must be cold.)
Squeeze the lemon juice in a large bowl and set aside.
Wash and finely chop all the vegetables and fresh herbs, add them to the bowl of lemon juice. Pour in the olive oil and mix well.
Take the couscous out of the fridge and mix it with the bowl of vegetables. Serve it cold.