In a small bowl, whisk together the olive oil, wine vinegar, Dijon mustard, minced garlic, salt, and pepper until emulsified. Set aside at room temperature—this gives the flavors time to meld while you prepare the other components. I find whisking the mustard in first helps it bind the oil and vinegar together for a more cohesive dressing.

Bring 1 inch of water to a boil in a pot and place a steamer basket over it. Add the broccoli florets and steam for exactly 1 minute, then immediately drain and spread on a clean kitchen towel or paper towels to cool slightly. This brief blanch softens the broccoli just enough to let the dressing penetrate while keeping it tender-crisp and vibrant green.

While the broccoli is still slightly warm, transfer it to a large bowl and pour the vinaigrette from Step 1 over it. Add the feta, grape tomatoes, red onion, and fresh parsley. Toss everything together gently but thoroughly to coat all components evenly with dressing. I like to halve the tomatoes lengthwise so they release their juices into the salad, adding extra flavor and moisture to every bite.