Boil or steam the potatoes until they are tender, then put them to one side.
Preheat the oven to 425°F
Fry the onions in a little of the oil until they have turned a dark, golden brown colour.
Top and tail the eggplant, slice it in half lengthwise, sprinkle the flesh with oil and place them on a greased baking sheet, flesh sides down. Prick the skin in a few places with a fork.
Bake the eggplant until the skin starts to shrivel and the flesh is soft (about 20-30 minutes). Scoop out the flesh when it has cooked. Turn the oven down to 350°F
Mash the potatoes, add the cooked onion, the eggplant flesh, garlic, parsley, season to taste with sea salt, freshly ground black pepper and paprika, then mix in sufficient matzo meal to make a firm [but not hard] consistency.
Wet your hands and shape tablespoonfuls of the mixture into patties. Put the patties on oiled baking sheets and sprinkle each one with a little oil. Bake them in the oven for 30 minutes until they are golden brown.
Serve them hot or cold with salads and horseradish.