Preheat oven to 400 degrees. Cook bacon until crispy; use a slotted spoon to remove bacon from pan and set it aside.
Toss potato chunks with bacon drippings. Spread onto a baking sheet lined with parchment paper or foil; season with salt and pepper.
Roast until potatoes are fork tender, about 30 to 35 minutes.
While potatoes are roasting, use a sharp knife to carefully cut kernels off the ears of corn.
In a large bowl, toss kernels, celery, red onion, green onions, and cooked bacon. Set aside.
Whisk together olive oil, apple cider vinegar, mustard, garlic, and ½ teaspoon pepper until emulsified. Season with salt to taste.
When potatoes are ready, mix them into the large bowl of vegetables. Pour vinaigrette over top, tossing to coat.
Serve immediately, allow to cool slightly and serve warm, or chill for later service.