In a medium bowl, toss the sliced potatoes with the olive oil, thyme, and a pinch each of salt and pepper. Lay the potatoes flat in one layer on a baking tray and place on middle rack of preheated 375 degree F oven. Bake 7 to 10 minutes, or until potatoes become soft and slightly crispy. Remove from the oven and set aside to cool.
Place two naan on a baking sheet. Spread the tomato sauce over each naan. Top with the sliced potatoes, and pieces of mozzarella. Season with rosemary, sea salt, and freshly ground pepper.
Place the naan on middle rack of preheated 400 degree F oven and bake 10 to 15 minutes, or until cheese melts and crust is golden brown.