Bring the chicken stock to boil in a saucepan. Add the mulukhiyya, reduce the heat, and simmer for 5 to 10 minutes to dissolve the herb. Heat the olive oil in a small skillet over medium heat. Add garlic cloves and cook for 2 minutes to 3 minutes, then add the mixture to the stock. Stir in coriander and cumin, cook for 2 minutes, then add the mixture to the stock. Stir in the juice of the lemon and salt and pepper to taste. Simmer the soup for 8 minutes. Divide the cooked rice among 8 bowls, ladle the soup over the rice and serve.