Cut broccoli into 1-inch florets. Wash thoroughly under cold running water, then dry completely with a clean kitchen towel or paper towels before proceeding.
Add the dried broccoli, diced red onion, shredded cheddar, sunflower seeds, slivered almonds, and dried cranberries to a large mixing bowl. Toss to distribute evenly.
In a separate small bowl, whisk together the mayonnaise, apple cider vinegar, sugar, salt, and black pepper for about 30 seconds until the sugar is dissolved and the dressing is smooth.
Pour the dressing over the salad. Toss thoroughly until every piece is evenly coated. Taste and adjust: more salt for lift, more vinegar for brightness.
Cover and refrigerate for at least 30 minutes before serving.
⚠️ Food Safety: Do not leave this salad at room temperature for more than 2 hours. Refrigerate promptly.
