Place the wheatberries in a large saucepan and cover with water. Bring to the boil and simmer until the wheatberries are tender, about 50 minutes. Drain any excess liquid; set aside and allow to cool slightly.
Meanwhile, combine the garlic, parsley and mint in a the bowl of a food processor. Pulse to mince. Mix in lemon juice and zest, oil and apple cider vinegar.
Combine the cooled wheatberries and the herb mixture with the olives, tomatoes and cucumber. Stir well. Season with salt and pepper. Enjoy straightaway or chill till serving.