Peel and finely dice the cucumber.
Peel and finely dice the onion and chop the tomatoes into small pieces.
Place the cucumber, tomatoes and onion into a bowl and prepare the vinaigrette.
In a small bowl, mix the olive oil, lemon juice and crushed garlic.
Pour the vinaigrette over the vegetables.
Finely chop the parsley and add to the bowl with vegetables.
Season with salt and pepper to taste and mix well.
Eat as a side with meat, fish or seafood.