Celeriac is a large, round root vegetable with white flesh and a mild celery flavour. It can be used raw in salads and also makes a fantastic mash. Cook 1 celeriac, peeled, cut into 2cm cubes, and 4 sebago (washed) potatoes, peeled, cut into 2cm cubes, in a saucepan of boiling water for 10-15 minutes or until tender. Drain well. Return to the pan. Add 125ml (1/2 cup) milk and 30g butter and use a potato masher to mash until smooth.