Start by washing and thoroughly drying the broccoli. Cut it into small bite-sized florets for easy eating. Chop the red onion finely and cook the bacon until crispy, then crumble it. Shred the cheese fresh if possible for the best texture.
In a large bowl, combine the broccoli, cheddar cheese, cranberries, bacon, sunflower seeds, and red onion. Toss everything gently so the ingredients are evenly distributed. This step ensures every bite has a balanced mix of flavors.
In a separate bowl, whisk together mayonnaise, sour cream, vinegar, sugar, salt, and pepper. Mix until smooth and creamy with no lumps. Taste and adjust seasoning if needed for sweetness or tang.
Pour the dressing over the salad mixture. Stir well until all ingredients are coated evenly. Cover the bowl and refrigerate for at least one hour before serving. This resting time improves flavor and texture.