Boil the potatoes, cut into cubes, in generously salted water for about 20 minutes, until tender but not falling apart.

Fry the potatoes over high heat in corn oil for 4-5 minutes, until golden brown. Transfer them to a salad bowl and sprinkle with oregano, salt, and black pepper.

Add the tomato, cut into cubes, along with the finely chopped parsley and onion.

Drizzle with white vinegar and olive oil, toss well, and serve.