When I run low on Champagne vinegar, apple cider vinegar is a good swap here. Also, if you want to thin the dressing a bit, add an extra splash of the buttermilk. You can also use other sturdy lettuces in place of the iceberg called for here, Romaine and heads of little gems are good alternatives.
Serve drizzled with the dressing and lots of crushed kale chips, toasted nuts (pine nuts and pistachios pictured here), and you can never have enough chives. You'll likely have plenty of leftover dressing, it keeps, refrigerated, for 4-5 days.
Serves 4 - 8