- 1/2 cup mayonnaise
- 6 tablespoons distilled white vinegar
- 3 green onions, minced
- 4 tablespoons chopped fresh dill
- 1/4 cup buttermilk
- 1/2 teaspoon salt
- 2 medium zucchini (about 10 ounces), trimmed, sliced into very thin rounds
- 2 1/4 pounds small white potatoes, peeled, sliced into generous 1/4-inch thick rounds
- 5 peeled hard-boiled eggs, 4 sliced and 1 grated
- 1 cup thinly sliced celery
- Combine mayonnaise, 2 tablespoons vinegar, green onions, 3 tablespoons dill and buttermilk in small bowl; whisk to blend. Season with salt and pepper. Cover and chill at least 1 hour or up to 1 day.
- Combine remaining 4 tablespoons vinegar, 1 tablespoon dill and 1/2 teaspoon salt in medium bowl; mix in zucchini. Let stand at least 1 hour and up to 3 hours at room temperature, tossing occasionally. Drain thoroughly.
- Steam potatoes until just tender, about 12 minutes. Cool to just warm, about 10 minutes. Transfer to large bowl. Add sliced eggs, celery and zucchini. Mix in dressing; Season with salt and pepper. Sprinkle with grated egg. (Can be prepared 2 hours ahead. Cover and let stand at room temperature.)