Pre-heat a large nonstick skillet over medium-high heat with three turns of the pan of EVOO, about three tablespoons. Add the potatoes, parsnips, thyme and season with salt and pepper, stir frequently and cook for 10-12 minutes, or until the potatoes and parsnips are nice and tender and lightly browned. Add the minced onion and continue to cook until they are tender and the potatoes are nice and brown.
Once the hash is cooked, add the chopped parsley and lemon zest. Stir to combine and transfer hash to a serving platter. Serve it up.