What method is used to create a stable mixture of oil and vinegar?

The method used to create a stable mixture of oil and vinegar is emulsification. Emulsification involves combining two liquids that typically do not mix, such as oil and vinegar. In this process, an emulsifier, a substance that helps stabilize the mixture, may be used. Common emulsifiers in culinary contexts include egg yolks (as in mayonnaise) or mustard.

When oil and vinegar are emulsified, the tiny droplets of one liquid are dispersed throughout the other, resulting in a creamy or stable mixture. This is significantly different from merely whisking the ingredients together, which may not achieve the same level of stability over time.

Boiling is not relevant here as it generally applies to the heating of liquids for cooking, not for mixing two unmixable liquids. Fermentation also doesn't apply, as it involves chemical changes in organic substances due to microorganisms, rather than blending liquids. Thus, emulsification is the correct choice for creating a stable mixture of oil and vinegar.