Cut the broccoli into small 1/2-inch florets, slice the carrots into thin matchsticks or small dice, finely dice the red onion into small pieces, and cut the apple into 1/4-inch pieces. I recommend cutting the apple just before mixing it with the dressing to prevent browning, but you can prepare it up to 15 minutes ahead and toss it with a squeeze of lemon juice to keep it fresh. Have all ingredients prepped and ready to go before assembling the salad.
In a small bowl, whisk together the Greek yogurt, cider vinegar, honey, and freshly squeezed lemon juice until smooth and well combined. Add the salt, pepper, and garlic powder, then whisk again until the dressing is creamy and all seasonings are evenly distributed. I prefer Greek yogurt over regular yogurt because it creates a richer, thicker dressing while keeping the calories low.
In a large bowl, add the prepared broccoli florets, carrots, cranberries, and sunflower seeds. Gently toss these ingredients together to distribute them evenly, then add the diced red onion and apple. Mix gently until all ingredients are combined—be careful not to crush the broccoli florets.
Pour the dressing from Step 2 over the vegetable mixture and toss gently but thoroughly until all the vegetables and fruit are evenly coated with the creamy dressing. Cover the bowl with plastic wrap or a lid and refrigerate for at least 1 hour—this allows the flavors to meld and the broccoli to soften slightly while the salad stays crisp and fresh.
Remove the salad from the refrigerator, give it a gentle stir to redistribute any dressing that has settled at the bottom, and taste for seasoning. Adjust salt, pepper, or lemon juice if needed, then serve immediately. This salad is best enjoyed cold and will keep well in the refrigerator for up to 2 days.