Gather your ingredients. You'll need fresh baby spinach, ripe strawberries, red onion, feta cheese (or goat cheese), sliced almonds (or walnuts), olive oil, balsamic vinegar, honey, salt, and pepper.
Rinse the baby spinach leaves thoroughly under cold water and pat them dry with paper towels or a clean kitchen towel. Transfer the spinach to a large salad bowl.
Remove the stems from the strawberries and slice them thinly. Add the sliced strawberries to the bowl with the spinach.
Peel the red onion and slice it thinly. Add the sliced red onion to the salad bowl.
If using sliced almonds or walnuts, toast them in a dry skillet over medium heat until lightly golden and fragrant, stirring frequently to prevent burning. Remove from heat and let them cool slightly.
In a small bowl, whisk together the olive oil, balsamic vinegar, honey, salt, and pepper until well combined. Adjust the sweetness and acidity to taste by adding more honey or vinegar if desired.
Add the toasted almonds (or walnuts) and crumbled feta cheese (or goat cheese) to the salad bowl with the spinach, strawberries, and red onion.
Drizzle the prepared dressing over the salad ingredients in the bowl. Gently toss everything together until the salad is evenly coated with the dressing.