Whisk the mayonnaise, sour cream, apple cider vinegar, erythritol/stevia blend, salt, and pepper in a medium sized bowl (or mason jar). Set aside.
Add the chopped broccoli and cauliflower, onion, crumbled bacon, and sliced almonds to a large bowl.
Drizzle with prepared dressing and toss to combine.
Salad can be served immediately or refrigerated up to 24 hours before serving. The vegetables get better the longer the flavors are allowed to combine in the fridge!