In a medium glass or enamel lined sauce pan over high heat, combine oil, peppers, garlic, onion and salt; saute for 4 minutes. Add the water and cook for 20 minutes, stirring often. Remove from heat and allow mixture to cool to room temperature.
Transfer the mixture to a food processor and puree until smooth. With the processor running, slowly add the vinegar.
Pour into a sterilized jar with a tight lid. This sauce will keep for 6 months when stored in the refrigerator.