¼ cup buttermilk
4 tablespoons olive oil, divided
sea salt and freshly ground black pepper
1 large Pink Lady apple, cored, thinly sliced
2 purple carrots, peeled, thinly sliced lengthwise on a mandoline
½ pound young arugula leaves
¼ cup fresh dill with tender stems
2 tablespoons apple cider vinegar
flaky sea salt (such as Maldon)