Top the spinach with sliced strawberries and the thinly sliced red onion.
Sprinkle the crumbled feta cheese and chopped walnuts over the salad mixture.
In a separate small bowl, whisk together the olive oil, apple cider vinegar, honey, poppy seeds, salt, and pepper until combined and slightly emulsified.
Drizzle the poppy seed dressing over the salad and gently toss to combine, ensuring all the greens and toppings are evenly coated.
Adjust the seasoning with additional salt and pepper, if desired, before serving.
Notes
Serve in large salad bowls, garnished with a few extra strawberries and a sprig of fresh mint for a pop of color.