For the stock, place the water, poussin carcass, garlic and herbs in a pan and bring to the boil. Boil for 8-10 minutes then strain the stock, discarding the bones and reserving the liquid.
Heat the oil in a medium pan and sauté the red onion for a few minutes to soften. Add the mushroom and sauté for a further 1-2 minutes.
Add the sesame oil, soy sauce, vinegar, Tabasco sauce, chilli and parsley and stir well.
Pour in the stock, bring to the boil, then reduce the heat and simmer gently for 10-12 minutes.
Ladle into a bowl and serve.