Heat the coconut oil in a large pot over medium heat.
Add the minced garlic and grated ginger, and cook for about one minute until fragrant.
Stir in the Thai red curry paste and cook for another minute to release the spices.
Add the chicken pieces and stir well to coat them in the curry mixture.
Pour in the chicken broth and bring the soup to a gentle simmer.
Stir in the coconut milk and fish sauce, then lower the heat.
Add the sliced mushrooms and let them simmer until tender.
Stir in the spinach or bok choy and cook until just wilted.
Remove the pot from heat and stir in the lime juice.
Taste and adjust seasoning with salt and pepper before serving.