Rinse the spinach leaves thoroughly under cold water.
Dry the spinach using a salad spinner or paper towels.
Place the spinach in a large bowl.
Add halved cherry tomatoes to the bowl.
Slice cucumbers and add them to the mixture.
Thinly slice the red onion and include it in the salad.
Sprinkle crumbled feta cheese over the top.
Add chopped walnuts for crunch and flavor.
Drizzle balsamic vinaigrette over the salad.
Season with salt and pepper to taste; toss gently to combine.