Winter Chicken Salad With Tangy Miso Dressing

Name: Winter Chicken Salad With Tangy Miso Dressing
Ingredients: For the salad; 1 pound boneless skinless chicken breasts; Kosher salt; Freshly ground black pepper; 1 head butter lettuce, washed and dried; 1 large handful arugula or watercress, washed and dried; 1 small or 1/2 large bulb fennel, very thinly sliced; 3 seedless mandarins, peeled, cut into wheels, and pulled into pieces; 1 small avocado, diced; For the miso dressing; 1 tablespoon white miso paste; 1 tablespoon plus 2 teaspoons apple cider vinegar; 1 teaspoon honey; 2 scallions, white and light green parts only, finely chopped; 1/2 teaspoon ground cumin; 1/4 cup plus 2 teaspoons extra-virgin olive oil