Combine the garlic and vinegar in a small bowl and let sit for 24 hours. Drain off the vinegar.
Combine the garlic, olive oil, whole peppers, cayenne, and salt in a 2-quart saucepan over medium heat. Simmer for 15 minutes, stirring occasionally. Remove from the heat and let steep for 45 minutes.
Pour half of the oil into a food processor with half of the peppers and half of the garlic slices and process until smooth, about 20 seconds.
Sterilize a quart-size bottle or jar. Place the remaining peppers and garlic in the container. Pour in the pureed mixture and the remaining oil. Cool and secure with an airtight lid. Store in the refrigerator for 2 weeks before using. Will keep for 1 month in the refrigerator.
Yield: 1 quart