1 cup water
2 tablespoons granulated sugar
¾ cup, plus 2 tablespoons apple cider vinegar, divided
2 ¼ teaspoons kosher salt, divided
1 medium-size (about 8 ounces) red onion, sliced (about 1 1/2 cups)
2 pounds sweet potatoes, peeled and cut into 1/2-inch half-moons (6 cups)
1 teaspoon smoked paprika
½ teaspoon ground cumin
4 tablespoons olive oil, divided
3 tablespoons hot honey (such as Mike's Hot Honey)
1 tablespoon whole-grain Dijon mustard
¼ teaspoon black pepper
½ cup chopped fresh flat-leaf parsley
½ cup toasted pecan halves
Preheat oven to 425°F. Stir together water, sugar, 3/4 cup of the vinegar, and 1 teaspoon of the salt in a small saucepan; bring to a boil over high. Reduce heat to medium-low; simmer, undisturbed, until sugar is dissolved, 2 to 3 minutes. Remove from heat. Place onion slices in a heatproof jar or bowl; carefully pour pickling mixture over onion, ensuring slices are fully submerged. Seal jar with lid, or cover bowl with plastic wrap; let stand at room temperature until ready to use.
Toss together sweet potatoes, smoked paprika, cumin, 1 teaspoon of the salt, and 2 tablespoons of the oil in a large bowl until well combined. Arrange sweet potatoes in an even layer on a baking sheet. Roast in preheated oven until fork-tender, 20 to 25 minutes. Remove from oven, and set aside.
Whisk together hot honey, mustard, pepper, and remaining 2 tablespoons vinegar, 1/4 teaspoon salt, and 2 tablespoons oil in a large bowl until smooth and combined. Drain pickled onion to measure 1/2 cup drained onion; reserve remaining pickled onion and pickling liquid in a sealed jar in refrigerator up to 1 month. Add sweet potatoes, parsley, and drained pickled onion to hot honey mixture in bowl; toss until evenly combined. Sprinkle salad with pecans, and serve.
