Making the sauce. Combine water and 3 tsp of cornstarch (note: save the other 2 tsp for later), then add to pot. Also, add soy sauce, brown sugar, garlic, rice wine, and honey. Bring to boil.
Stir continueously, and let it boiled for a few minutes until sauce thickens slightly. Then remove from heat.
Making the ribs. Cut the rack of ribs into two or three sections so that it will fit into slow cooker easily.
Spray slow cooker with vegetable oil. Brush sauce generously all over ribs, then add a few tablespoon of sauce to the bottom of the slow cooker so that there is a thin layer of liquid. Add ribs to slow cooker, then pour the rest of the sauce into slow cooker.
Cook on high for 4 hours. Halfway through cooking, rearrange ribs so that they are submerged in the sauce. This will ensure ribs are evenly infused with the yummy sauce. Note: You may need to rearrange a few times to make sure all the ribs take turns being submerged in sauce.
When ribs are done, pre-heat oven to 400 degrees F. Transfer ribs from slow cooker onto a baking pan lined with aluminium foil (for easy cleanup).
Pour the sauce in the slow cooker to a pot. Remove a few tablespoons of sauce form the pot to a small bowl and add 2 tsp of corn starch to the bowl. Mix well, then add sauce + cornstach back into the pot.
Bring sauce to a boil on stovetop, stir continuously, and keep cooking until sauce thickens. Remove pot from heat.
Brush sauce generously all over ribs. Then bake ribs for 7 minutes.
Cut ribs into smaller pieces and garnish with green onions. Serve with the remaining sauce. Enjoy!