Whisk together the lemon juice, olive oil, salt, pepper, and green peppercorns. Taste and adjust seasonings. Roll each zucchini slice into a coil and place on serving plate. Pour dressing over zucchini. Drop Parmesan shavings over the plate. Serve immediately.
To make zucchini ribbons, cut a thin slice off the zucchini, discard. Place zucchini cut side down on a cutting board so it doesn't roll. Drag a sharp carrot peeler across the zucchini, pressing down hard as if you were peeling a carrot. You will get nice long ribbons and if you don't so what! The dressing is delicious and presentation doesn't always matter! Do the best you can and move on.