How to Make It
Fill a large saucepan with 1 inch of water and fit with a steamer basket. Bring to a simmer. Place the potatoes in the steamer basket, cover, and steam until cooked through, 15 to 18 minutes.
Whisk together the oil, lemon juice, dill, ¾ teaspoon salt, and ½ teaspoon pepper in a small bowl. Arrange the potatoes, avocado, radishes, eggs, corn, bocconcini, and radicchio on a platter. Drizzle with the dressing.