In a large bowl, whisk together the mayo, sour cream, red wine vinegar, salt, black pepper, and sugar until smooth and well combined. The dressing should be creamy with no lumps. Set aside while you prepare the remaining components. I like to make the dressing first so the flavors can start melding together while I'm prepping everything else.

Preheat your oven to 400°F. Lay the bacon slices on a baking sheet in a single layer and bake for 15-20 minutes until golden and crispy. Remove from the oven, let cool slightly on a paper towel, then crumble into roughly 1/2-inch pieces. Cooking bacon in the oven is my preferred method because it cooks evenly and you don't have to monitor it constantly.

While the bacon cooks, cut the broccoli into small bite-sized florets (about 1-1.5 inches). Finely dice the red onion into 1/8-inch pieces and cut the cheddar cheese into 1/4-inch cubes. Having all your components prepped and ready to go ensures the final assembly comes together smoothly.

Add the broccoli florets, craisins, sunflower seeds, crumbled bacon from Step 2, and diced red onion to the dressing bowl from Step 1. Add the cheddar cheese cubes last. Using a large spoon or spatula, gently fold everything together until all the vegetables and cheese are evenly coated with the creamy dressing. Be careful not to crush the broccoli while mixing.

Transfer the salad to a serving dish and refrigerate for at least 1 hour before serving. This allows the flavors to fully develop and the broccoli to soften slightly while remaining crisp. The salad keeps well in the refrigerator for up to 2 days, though you may notice the broccoli releases some moisture over time.