Step 1

Whisk oil, vinegar, mayonnaise, sugar, oregano, and garlic in a small bowl. Season with salt and pepper.

Step 2

Cut lettuce in half through stem end. Tear apart into large pieces. Arrange on a platter and scatter onion, provolone, mozzarella, and peperoncini over, nestling in among leaves. Drizzle with dressing to coat to your liking (you’ll probably have some extra) and top with more black pepper.

Step 3

Do Ahead: Dressing can be made 1 week ahead. Cover and chill.