For the dressing: Combine the mayonnaise, sour cream, buttermilk, dill, oregano, paprika, pepper and hot sauce in a bowl and mix to combine.
For the assembly: Arrange the lettuce on a platter. Drizzle about half of the dressing over the lettuce. Sprinkle the hearts of palm, artichoke hearts, roasted peppers, cherry tomatoes, prosciutto and shaved Parmesan evenly over the greens. Serve the remaining dressing on the side.