Store-bought ’nduja, the spicy, spreadable sausage, is transformed into a special canapé when served on toasted baguette and topped with a quick-pickled celery.
Toss together celery, vinegar, sugar, and kosher salt in a medium bowl until salt and sugar dissolve. Let stand 15 minutes. Meanwhile, lightly toast or grill baguette slices.
Drain pickled celery. Spread ’nduja evenly on toasts using a small offset spatula. Arrange toasts on a platter or board. Sprinkle pickled celery evenly over toasts. Drizzle with oil; sprinkle with flaky sea salt. Garnish with celery leaves.
Prepare and drain the celery mixture; refrigerate overnight.