In 1-cup liquid measuring cup, whisk together lemon juice, vinegar, sugar, and 2 tablespoons water. Using mortar and pestle or food processor, grind or crush garlic, lemon zest, and kosher salt into fine paste. Whisk paste into lemon juice mixture. Gradually whisk in oil. Whisk in table salt and pepper to taste. In large bowl, toss together lettuce, radishes, minced herbs, and dressing. Divide mixture among 6 salad plates. Using vegetable peeler, shave curls of Parmesan atop each salad and serve.