Prepare the couscous in accordance with the instructions on the packet. Set the couscous aside to cool down.
Finely chop the parsley and the mint and slice the onions. Cut the tomato into quarters, scoop the seeds out and chop into small cubes.
In a small bowl mix together the olive oil and lemon juice.
Add the parsley, mint, chopped onion and tomatoes into the couscous. Pour olive oil and lemon juice mixture over the couscous and mix well. Season to taste.