Prepare the vegetables. In a large mixing bowl, combine the broccoli and cauliflower florets, sliced red onion, grapes, and slivered almonds. Gently toss the ingredients to ensure even distribution.
Create the dressing. In a separate bowl, whisk together the Greek yogurt, mayonnaise, apple cider vinegar, salt, and pepper until well combined. Taste the dressing and adjust the seasoning according to your preference.
Toss the salad. Pour the dressing over the broccoli and cauliflower mixture, ensuring all the ingredients are evenly coated. Use a spatula or large spoon to gently toss the salad, allowing the dressing to coat every nook and cranny.
Let the salad chill. Once fully combined, refrigerate the salad for at least 30 minutes to allow the flavors to meld together and the salad to chill. This step is crucial as it enhances the taste and texture of the salad.
Garnish and serve! Just before serving, sprinkle the chopped fresh parsley over the salad for a pop of color and an extra layer of freshness.