Cook's Note: If you don't have curry powder, use a mix of 1 teaspoon each cumin, coriander and turmeric and 1/2 teaspoon each ground mustard and ground ginger.
Combine the yogurt, curry powder and lemon juice in a large bowl and season with salt and pepper. Add the chicken, scallions, apples and carrots and mix until combined. Adjust the seasonings.
Butter the rolls and toast on a hot griddle. Fill with lettuce, chicken salad and a sprinkle of almonds and crystallized ginger. Serve with chips.
The chicken salad can be covered and refrigerated for a make-ahead meal.
Put the chicken in a medium stockpot. Add the garlic, celery, bay leaf, carrots, lemons, onions and herb bundle and sprinkle with salt. Add enough water to cover the chicken. Bring to a boil, then reduce the heat to a simmer and cook for 45 minutes. Remove the chicken from the liquid and let cool. Strain the stock. Remove the skin and bones from the chicken, and shred the meat using your fingers or 2 forks.