Alternating between each, place the potatoes and zucchini in overlapping circles in a large, wide pot or deep skillet. Season with sea salt and pepper. Add the olive oil and oregano. Cover the pot or frying pan and cook the vegetables until tender and until the bottom of the potatoes and zucchini are slightly charred. Flip over onto a plate, sprinkle with a little more oregano, drizzle, if desired with additional olive oil, and serve.