Place potato in a saucepan of cold, salted water, bring to the boil, and then cook over medium-high heat for 10-12 minutes or until tender. Drain and cool.
Transfer potato to a bowl and roughly mash with a fork or potato masher. Add the mustard, Fountain tomato sauce, parsley and beaten egg. Season with salt and pepper and stir to combine. Fold through ham. With damp hands, form the potato mixture into 18 even patties, about 2cm thick. Lightly dust in flour.
Add 2cm of oil to a fry pan and place over medium heat. In batches, cook potato cakes for 2 minutes each side or until golden and warmed through. Remove with a slotted spoon and drain on paper towel.
Serve immediately with extra Fountain Tomato Sauce and salad.