Begin by slicing the strawberries into thin, even pieces, revealing their juicy, bright interior. Set them aside.
Next, wash the spinach leaves thoroughly and dry them well using a salad spinner or patting with a towel—aim for crisp, slightly tender leaves.
Place the washed spinach in a large salad bowl, creating a fresh green base for your salad.
Add the sliced strawberries on top of the spinach, scattering them evenly across the greens.
Thinly slice the red onion and sprinkle it over the salad, adding a sharp contrast to the sweet strawberries.
Crumble the feta cheese over the entire salad, distributing it to add a salty, creamy element.
In a small bowl or jar, whisk together the balsamic glaze and olive oil until well combined and slightly emulsified.
Drizzle the dressing evenly over the salad, giving everything a gentle toss to coat the ingredients without crushing the strawberries.
Finish by cracking fresh black pepper over the top, adjusting to taste, and giving the salad one last gentle toss.
Serve immediately to enjoy the fresh crunch of the greens and the juicy burst of strawberries, or chill for up to 30 minutes to let flavors meld.