01 - In a large serving bowl, combine the baby spinach, sliced strawberries, red onion rings, crumbled feta cheese, toasted almonds, and sunflower seeds if using. Distribute ingredients evenly for attractive presentation.
02 - In a small mixing bowl or glass jar with tight-fitting lid, whisk together the balsamic vinegar, honey or maple syrup, and Dijon mustard until well combined. While whisking continuously, slowly drizzle in the extra-virgin olive oil to create an emulsified dressing. Stir in the poppy seeds and season generously with salt and pepper to taste.
03 - Immediately before serving, drizzle the balsamic poppy seed dressing over the salad. Use salad tongs to toss gently and evenly coat all ingredients without crushing delicate spinach leaves. Serve at once while spinach remains crisp, adding extra strawberry slices or almonds as garnish if desired.