Bring water, salt and olive oil to a full boil
Add the couscous, cover and remove from heat, let it stand for 5 minutes
Meanwhile, chop the onions and shell the pistachios
After 5 minutes, fluff the couscous with a fork and transfer it to a serving dish
Add the mint, pistachios, onions, salt, garlic and lemon juice and toss together
Serve warm or at room temperature, refrigerate leftovers