In a small bowl, whisk together olive oil, apple cider vinegar, honey, poppy seeds, and Dijon mustard until smooth and creamy. The mixture should emulsify beautifully, creating a glossy dressing that coats the back of your spoon. Season with salt and pepper to taste.

Heat a small skillet over medium heat and add the chopped pecans. Toast for 3-4 minutes, stirring frequently, until they smell nutty and turn golden brown. Watch carefully as they can burn quickly.

Wash and thoroughly dry the baby spinach using a salad spinner or paper towels. Hull and slice the strawberries into uniform pieces, about 1/4-inch thick. Thinly slice the red onion, soaking it in cold water for 5 minutes if you prefer a milder flavor.

In a large serving bowl, combine the dried spinach, sliced strawberries, and red onion. Drizzle half the dressing over the mixture and gently toss with clean hands or salad tongs. Add the crumbled feta cheese and toasted pecans, then drizzle with remaining dressing as needed.