Add the coconut milk to a small pot over medium high-heat. Bring the coconut milk to a light simmer stirring often, then reduce the heat to medium. Let the coconut milk simmer for 10 minutes to let it thicken.
Place the cubed kabocha squash into a large frying pan over medium-high heat. Add 1 cup of water to the pan, cover, and steam the squash for 10 minutes.
After 10 minutes, check the squash for doneness by inserting a fork into the middle of a piece of squash. It should go most of the way through, but still have a bit of resistance in the middle.
Transfer the partly cooked squash to a plate. Discard the water and clean the pan to cook the rest of the curry.
Add the coconut oil to the cleaned pan over medium-high heat. Once hot, reduce the heat to medium and add the Thai red curry paste. Mix the curry paste and coconut oil together with a wooden spoon, breaking up the paste. Cook, stirring often for 2 minutes to bring out the flavours of the curry paste.
After 2 minutes, add the chopped garlic, ginger and Thai Birds Eye chilis and mix to combine. Cook for 30 seconds.
After 30 seconds, add the sliced onion, followed by the red bell peppers. Mix to combine and cook for 3-4 minutes until the peppers and onions have softened slightly.
Add the reduced coconut milk to the pan along with the steamed kabocha squash, sugar, and 1 cup of water and gently mix to combine. Simmer for 5 minutes to let the flavours come together.
Finally, add the baby bok choy to the pan and mix to combine. Simmer for 2 minutes or until the bok choy is tender and cooked through.
Scoop the curry into bowls and serve with steamed rice, and a garnish of Thai basil, mint, and fresh lime.