Put the lentils in a medium pan with the garlic, bay and celery and cover with a litre of cold water. Bring the lentils to the boil, then reduce the heat to a simmer and cook for 20-25 minutes or until the lentils are tender. Drain, discarding the garlic, bay and celery.
Meanwhile make the dressing in a serving bowl. Grate the zest from the oranges, tear the mint into little pieces, chop the parsley. Mix with the olive oil, lemon juice and a good pinch of salt.
Tip the drained lentils into the bowl and mix well with the dressing. Leave to sit for 5 minutes, toss again and pour over a little more olive oil for shine before serving.