Halve and core the Bibb lettuce. Gently separate the leaves. Rinse and spin dry the lettuce leaves. Divide the lettuce among 4 plates, arranging the leaves so as to create a bowl on each plate. Sprinkle the lettuce bowls with the salt and pepper.
Divide the hearts of palm pieces, tomatoes, avocados, and cucumbers evenly among the 4 plates, forming neat individual piles of each within the lettuce bowls. Spoon 3 generous tablespoons of vinaigrette or dressing over each salad. Serve immediately.
Whisk the buttermilk, mayonnaise, sour cream, minced green onion tops, lemon juice, garlic, lemon zest, salt, pepper, and Creole seasoning, if using, together in a nonreactive mixing bowl. Use immediately, or store in a covered nonreactive container in the refrigerator for up to 3 days.
Combine all ingredients thoroughly.
Recipe from "New New Orleans Cooking", by Emeril Lagasse and Jessie Tirsch, published by William Morrow, 1993.
In a medium bowl, whisk together the vinegar, shallot, mustard, salt, and pepper. While constantly whisking, add the vegetable oil and olive oil in a thin, steady stream until they are completely incorporated and the dressing is emulsified. Stir in the fresh herbs, and adjust the seasoning to taste, if necessary. Serve the vinaigrette immediately or refrigerate in a covered nonreactive container for up to 2 days.