Heat coconut oil in a large and deep skillet on medium heat. Add onions and any hearty vegetables like carrots and potatoes and cook for 7-10 minutes, until slightly soft.
Add in zucchini and any other more delicate vegetables, and cook for another 5 minutes.
Add in the bok choy or other greens like spinach, at the end, cover and cook for 10 minutes, or until wilted.
Meanwhile, warm coconut milk and curry paste in a small saucepan on medium heat, allowing for a gentle simmer and stirring occasionally.
Pour curry sauce over vegetables, and add in the fish sauce if using. Stir to coat and heat through.
Serve over brown rice or brown rice pasta.