Cook the Bacon: If using the oven method, preheat the oven to 425°F. Line a large baking tray with foil, arrange the bacon on it, and place the tray in the cold oven while it preheats. Cook for 18–22 minutes, watching closely toward the end, until the bacon is done.
Prepare the Bacon: Remove the cooked bacon, drain it, then chop or crumble it into small pieces.
Combine the Salad Ingredients: Add the chopped bacon, cauliflower florets, dried cranberries or raisins, and finely chopped red onion to a large mixing bowl.
Make the Dressing: In a small bowl or large glass measuring cup, combine the mayonnaise, optional warm bacon grease, white sugar, vinegar, and kosher salt.
Whisk the Dressing: Whisk the dressing ingredients together until the mixture is smooth and evenly combined.
Dress the Salad: Pour the dressing over the cauliflower mixture and toss thoroughly until the ingredients are well coated.
Chill Before Serving: Refrigerate the salad until you are ready to serve it, allowing it to chill before serving.
Store the Salad: Keep the salad refrigerated for 2–3 days. Stir it before serving.