Heat the oil in a large pan, add the spinach and wilt over a medium heat. Drain the spinach, cut finely, add to a bowl.
Mix the roesti and add all ingredients up to and including the pepper to the spinach, mix well.
Heat the oil in a non-stick frying pan. Add portions of approx. 2 tbsp, reduce the heat, fry the medallions for approx. 4 mins. on each side over a medium heat.