Toast sliced almonds in a dry skillet over medium heat for 2 to 3 minutes until golden. Set aside to cool.
Whisk together olive oil, apple cider vinegar, lemon juice, honey, Dijon mustard, poppy seeds, salt, and pepper until emulsified.
Hull and slice strawberries. Rinse and dry blueberries and raspberries. Slice red onion as thinly as possible.
Place baby spinach in a large salad bowl. Top with sliced strawberries, blueberries, raspberries, and red onion.
Sprinkle toasted almonds, candied pecans, and crumbled feta over the salad.
Drizzle dressing over the salad just before serving. Toss gently and serve immediately.