Halve lengthways and finely slice the medium leeks. Grate the medium parsnips.
- 1 Tip the potato mash into a bowl. Add the leek, parsnip and plain flour and with clean hands, mix together well. Divide the mash into 8 equal pieces then form each into a crumpet-sized cake.
- 2 Heat the oil in a large non-stick frying pan. Fry the potato cakes in two batches for 4-5 minutes or until nicely browned and crusty. Carefully flip over with a fish slice and cook for a further 3-4 minutes.
- 3 Transfer to a warm plate or oven whilst you cook the remaining cakes.