In a mortar and pestle grind together the lemon zest and sea salt. Set aside. If you do not have a mortar and pestle you could use a heavy plastic storage bag and rolling pin to crush the two ingredients together. Use only the amount of sea salt to taste, store the remaining salt for another use.
Heat 2 tablespoons of oil in a large skillet of medium high heat and add the hash brown potatoes. Sprinkle ½ of the thyme over the potatoes. Allow to brown in the oil and turn when golden brown, approximately 7-10 minutes. Drizzle with remaining oil and the remaining thyme and then turn to brown on other side. When the potatoes are finished browning, sprinkle potatoes with lemon sea salt and serve.