1. Prepare the Spinach: Start by gently washing the baby spinach if it’s not pre-washed. Use a salad spinner to thoroughly dry the leaves. Excess water can dilute the dressing, so ensure the spinach is as dry as possible. Place the dried spinach in a large mixing bowl.

2. Hull and Slice the Strawberries: Wash the fresh strawberries under cool water. Use a small paring knife to hull them (remove the green leafy top and the white core). Slice the hulled strawberries into uniform pieces, about 1/4-inch thick. Add them to the bowl with the spinach.

3. Add Optional Red Onion and Pecans: If using, thinly slice the red onion and add it to the bowl. Roughly chop the pecans and sprinkle them over the spinach and strawberries. You can toast the pecans lightly in a dry skillet for a few minutes before adding them if you prefer a deeper, nuttier flavor, but this is optional.

4. Whisk Together the Dressing Ingredients: In a separate small bowl or a jar with a tight-fitting lid, combine the olive oil, apple cider vinegar, granulated sugar, poppy seeds, Dijon mustard, salt, and black pepper.

5. Emulsify the Dressing: Whisk the dressing ingredients vigorously until they are well combined and the sugar has dissolved. If using a jar, simply shake it well until the dressing is emulsified and slightly creamy. Taste the dressing and adjust the seasoning if needed, adding a little more sugar for sweetness or vinegar for tang.

6. Dress and Toss the Salad: Just before serving, pour the prepared poppy seed dressing over the spinach, strawberries, red onion, and pecans in the large mixing bowl.

7. Serve Immediately: Gently toss the salad until all the ingredients are evenly coated with the dressing. Serve the salad immediately to ensure the spinach remains crisp and fresh.