Place a steamer basket in a saucepan. Add water to just below the bottom of the basket. Bring water to a boil. Add broccoli to steamer basket. Cover and reduce heat. Cook three minutes. Transfer to a colander; rinse with cold water. Drain well.
In a large bowl, combine the broccoli, raisins, sunflower kernels and red onion. Toss to combine.
In a small bowl, combine the olive oil, Greek yogurt, honey mustard, garlic and lemon juice. Whisk until smooth. Pour dressing over broccoli mixture and toss to coat. Refrigerate for at least two hours or up to 24 hours before serving.