Adapted from TheKitchn.com
For the vinaigrette:
1/4 cup olive oil
2 tablespoons red wine vinegar
2 teaspoons finely chopped shallot
1 tablespoon honey
1 small clove garlic, minced
1/4 teaspoon kosher salt
Freshly ground black pepper
For the pickled red onions:
1 red onion, thinly sliced (use a mandoline if you have one)
3/4 cup raw apple cider vinegar
2 1/4 tablespoons raw honey
2 1/4 teaspoons sea salt
3/4 cup filtered water
For the salad:
6 cups baby kale mix (about 5 ounces)
6 cups arugula (about 5 ounces)
1 cup blueberries or chopped strawberries
1/2 cup shelled toasted pistachios, almonds or pecans, coarsely chopped
1/2 cup crumbled feta cheese or goat cheese (about 2 ounces)
Make the vinaigrette:
Place all the ingredients in a jar, seal, and shake to emulsify; set aside.
Pickle the onion:
Slice the red onions as thin as you can.
Stuff all the red onions in the jar of your choice. A bowl will work too.
In a measuring cup, combine apple cider vinegar, salt, honey, and water. Stir vigorously to dissolve the honey and salt.
Pour this pickling mixture over your sliced onions and let them set for an hour. After an hour, cover and store in the fridge for up to three weeks.
Assemble the salad:
Pile the kale mix and arugula onto a serving platter or large, shallow salad bowl and toss with 1/3 cup of the dressing.
Arrange the pickled red onion, berries, nuts, and cheese on top of the greens.
Serve alongside the remaining vinaigrette.
Make ahead: The vinaigrette can be made and refrigerated up to 3 days ahead. The onions can be pickled and stored in the pickling liquid in the refrigerator for up to 3 weeks.