Orange Fennel Spinach Salad with Honey White Balsamic Dressing

For the pickled red onion:

• 1 medium red onion peeled and sliced into thin wedges
• ½ cup white balsamic vinegar
• 2 teaspoons honey
• ½ teaspoon salt
• ¼ cup water

For the Honey White Balsamic Dressing:

• 1 batch of this Honey White Balsamic Dressing recipe

For the rosemary almonds:

• ½ cup whole almonds
• 2 teaspoons extra virgin olive oil plus more for finishing
• 2 teaspoons finely chopped fresh rosemary plus more for finishing
• ½ teaspoon fine salt or table salt not kosher salt, plus more as needed

For the salad:

• 6-8 ounces baby spinach
• 4 medium mandarin oranges (or 3 medium navel oranges) peeled, halved and sliced into ¼-inch slices
• 1 small fennel bulb stems and fronds removed halved, then thinly sliced crosswise, discarding the hard core, optional
• ¼ cup pomegranate arils optional