Heat the vegetable oil in a large pot over medium-high heat.
Add the sliced onion and cook it until softened and lightly browned.
Place the whole chicken in the pot.
Add the sliced coriander stalks to it.
Carefully cut the butternut squash in half and remove the seeds.
Chop it into 3 cm chunks.
Add these chunks to the pot along with the Thai red curry paste.
Pour in the coconut milk and water.
Cover the pot and let it simmer over medium heat for 1 hour and 20 minutes until the chicken is thoroughly cooked and tender.
Carefully remove the chicken from the pot, shred the meat, and return it to the soup.
This will release the flavors into the broth beautifully.