in a small pot, in oil, saute the onions, peppers, garlic and curry powder til the onions are soft - about 2-4 minutes
Add everything else and whisk to combine.
Bring the sauce to a simmer and allow to simmer on low for 8-10 minutes. Stirring occasionally.
Once cooled, blend everything til smooth and transfer to a sauce bottle. Refrigerate overnight to allow all flavours to combine.