Place sugar into a saucepan on medium-high heat. Allow sugar to melt. Mix sugar crystals with melted sugar to ensure an even caramel. Continue heating until melted sugar becomes a medium brown caramel color.
Then add coconut water, xiaoxing wine, butter, fish sauce, oyster sauce, dark soy sauce, soy sauce, and garlic. Mix well. The sugar will become solid, but will eventually dissolve again. Continue mixing and add in onions and garlic. Mix well and continue boiling on high heat until the sauce reduces to the point where it can coat the back of a wooden spoon (~10 minutes)
Then add in fish steaks into the sauce. Cover with lid. Braise for 5 minutes each side, depending on thickness of fish. After 5 minutes of cooking, baste the tops and sides of fish with sauce. Flip fish once. Do not turn too much. Then cover lid again and braise on medium high another 5 minutes.
If sauce becomes too sticky add more coconut water or water.
Allow catfish to braise in the sauce until sauce is thickened and easily coats a wooden spoon.
Adjust seasonings to taste: by adding in a splash of water, oyster sauce, fish sauce, or sugar.
Garnish with fried shallots and green onion and serve with white rice. Enjoy!