Cut the florets off of the head of cauliflower. You can use a food processor, but be careful not to over process. You want the florets to be about the size of a potato chunk in a regular potato salad. Between the size of a dime and a nickle. Any larger and they might be under cooked, any smaller and they might overcook.
Place the cauliflower florets in the inner pot of the Ninja Foodi. Put the rack in the high position and lay the bacon on the rack. I like to cut the bacon in ½ to arrange it in a single layer on the rack.
Air Crisp the bacon on 360° F for 20-25 minutes, flipping at the 10 minute mark and the 20 minute mark. After 10 minutes, remove the rack and toss around the cauliflower. Sometimes the edges get more brown than the middle, so moving the bacon and the cauliflower around is helpful.
While the bacon and cauliflower are cooking, make up the dressing. Mix the yogurt, sour cream, vinegar, salt, and pepper into a medium size mixing bowl.
Remove the bacon from the Ninja Foodi and place strips on a paper towel to drain. Stir the cauliflower and check for doneness. If they are still on the crunchy side, continue to Bake Roast on 360° F until they have the same texture as a potato cube. Soft, but still firm.
Allow the cauliflower to cool slightly. You can do this right in the inner pot or transfer to a mixing/serving bowl.
Dice up the onion and the celery and add to the cauliflower. Add the dressing. Crumble Bacon on top and stir to combine. Refrigerate for a few hours.
Top with diced green onions if desired. Serve & Enjoy!