Heat the cooking oil in a pot. Add the onion and cook over medium-low heat, covered and with occasional stirring, until lightly browned. Add the garlic and ginger. Cook for another minute.
Pour in the broth. Throw in the chickpeas, potato and chayote cubes. Season with Himalayan black salt and pepper. Bring to the boil, cover and simmer for 10 to 15 minutes until the vegetables are done. Taste the broth. Adjust the seasonings, if needed.
Ladle the soup into bowls. Garnish with slices of lime, finely sliced mint leaves and fried shallots.