- 2 skinless, boneless chicken breasts (about 1 pound), halved horizontally
- 1/4 recipe Curry Brine
- 4 stalks celery, thinly sliced
- 1/2 small fennel bulb, thinly sliced
- 1 tablespoon plain whole-milk yogurt
- 1 teaspoon fresh lemon juice
- 3/4 teaspoon celery seeds
- 1 tablespoon mayonnaise plus more for serving
- Kosher salt, freshly ground pepper
- freshly ground pepper
- 4 large or 8 small slices country-style bread
- 1/4 cup olive oil
- 1/2 small red onion, thinly sliced
- 1/2 cup picked dill with tender stems
- Combine chicken and Curry Brine in a large resealable plastic bag, seal, and turn to coat. Chill at least 4 hours. Prepare grill for medium-high heat.
- Combine celery, fennel, yogurt, lemon juice, celery seeds, and 1 tablespoon mayonnaise in a medium bowl; season with salt and pepper and toss to combine. Set slaw aside.
- Grill chicken until cooked through, 5-7 minutes per side. Brush bread on both sides with oil and grill until toasted, about 2 minutes per side; spread with mayonnaise. Build sandwiches with bread, chicken, slaw, onion, and dill.
- DO AHEAD: Chicken can be brined 1 day ahead. Keep chilled.