Step 4: Make the sauce: 1 tbsp of ketchup, 1 tbsp of oyster sauce, 1 tbsp of soy sauce, 1 tbsp of rice vinegar, 2 tbsp of sugar. Sauté shallots with cooking oil. Pour the sauce and the water marinating the ribs to boil and then add the ribs, 1/2 cup of water to simmer with low heat until the ribs are soft and absorbent. When the water almost runs out, add the onions. Season again, then turn off the heat. Add some pepper to taste.