Mix the couscous with the olive oil and the squeezed lemon juice the evening before, cover and chill.
Very important: DO NOT pre-cook the couscous !!
The next day chop the vegetables, peel and core the tomatoes and dice them. Peel and core the cucumber and dice. Finely chop the onion. Stir all the vegetables into the couscous.
Finely chop the herbs and stir in and season well with salt and pepper. Chill at least 2 hours before eating.