Heat a pan and add garlic and ginger. Sauté on low heat, until fragrant. Be careful not to brown or burn the ginger or garlic.
Add the minced onions and let them cook on low heat. In the meanwhile, discard most of the water used to soak the chillies and grind them with just 2 tbsp water to a paste.
Once the onions look like they are almost melting, add ground chilli paste, soy sauce, vinegar, salt and water.
Bring this to a boil and simmer, until the sauce thickens.
Turn the heat off and let the sauce cool. Once completely cool, transfer to an airtight container and store in the refrigerator for up to 15 days.