Pickle Potato Salad

4 medium russet potatoes (about 2½ lb.), peeled, cut into 2" pieces
1 large or 2 medium carrots (about 8 oz.), peeled, cut into 1" pieces
3 Tbsp. vegetable oil
3 Tbsp. Pickle Brine Spice Rub
1½ tsp. kosher salt, divided
½ small red onion, thinly sliced
4 celery stalks, thinly sliced on a diagonal
2 tsp. white wine vinegar
3 Tbsp. extra-virgin olive oil
3 Tbsp. mayonnaise
1 tsp. Dijon mustard
3 cups shredded rotisserie or leftover cooked chicken
4 kosher dill pickle spears, sliced ¼" thick
¾ cup parsley leaves with tender stems

Preheat oven to 400°F. Toss potatoes and carrots with vegetable oil on a rimmed baking sheet to coat. Sprinkle evenly with spice rub and ½ tsp. salt. Roast until vegetables are deeply browned, tender, and crisp on the exterior, about 30 minutes.
Meanwhile, toss onion, celery, vinegar, and remaining 1 tsp. salt in a large bowl to combine. Let sit 10 minutes
and whisk olive oil, mayonnaise, and mustard in a small bowl to combine. Mix in chicken; set aside.
Add pickles, parsley, and hot roasted potatoes and carrots to bowl with onion mixture and toss to combine. Gently mix in reserved dressed chicken just to distribute.

Pickle Brine Spice Rub

4 Tbsp. coriander seeds
6 Tbsp. vinegar powder
4 Tbsp. dried dill
2 Tbsp. kosher salt
4 tsp. celery seeds
1 tsp. mustard powder

Toast coriander seeds in a small skillet over medium-high heat, tossing occasionally, until fragrant and slightly darkened in color, about 2 minutes. Transfer to a spice mill or mortar and pestle and let cool; coarsely grind. Transfer to an airtight container and mix in vinegar powder, dried dill, salt, celery seeds, and mustard powder; cover.