Soak the pearl barley for 30 minutes. In a medium-sized pot (preferably a cast iron pot), heat the vegetable oil, whole chicken breast and season with turmeric powder, coriander powder, 1 tsp of salt and ½ tsp of black pepper powder; brown the chicken on high heat.
Add the ginger, garlic, onions, bay leaf, celery, carrots, potatoes and courgettes. Sauté the ingredients together on medium heat for a couple of minutes, and add the pearl barley, chicken stock and tomato paste. On high heat, bring the liquid to a boil, and then lower heat to medium–low and leave to simmer for about 45–60 minutes. Add more chicken stock or water if needed.
Once the vegetables and chicken have cooked, remove the chicken breast out of the soup and shred. Return the shredded chicken back into the pot. Season the soup with salt and pepper and add the parsley. Leave to simmer for an additional 10 minutes.
Serve in a bowl with a slice of lemon for that added tangy flavour.