Bring a large pot of salted water to a boil.
Add the pasta and cook according to package directions for al dente texture.
Add the broccoli florets to the boiling pasta water during the final 2 minutes of the pasta cook time.
Drain the pasta and broccoli together and immediately rinse with cold water to stop the cooking process, then drain thoroughly.
In a small mixing bowl, whisk together the mayonnaise, lemon juice, lemon zest, minced garlic, Dijon mustard, honey, salt, and pepper until the dressing is emulsified.
In a large mixing bowl, combine the cooled pasta, broccoli, diced red onion, and halved cherry tomatoes.
Pour the dressing over the salad and toss until all components are evenly coated.
Stir in the sunflower seeds just before serving to maintain their texture.
Serve immediately or refrigerate for up to 4 hours.