Steps
1. In a bowl, whisk together the egg yolk, Dijon mustard, and white wine vinegar until fully combined.
2. Slowly drizzle in the vegetable oil while whisking continuously. Start with a few drops at a time, then gradually increase to a steady stream as the mixture emulsifies.
3. Once the mayonnaise has thickened, season with salt and add lemon juice to taste.
4. If the mayonnaise is too thick, you can thin it out with a few drops of water or more lemon juice.
5. Store in an airtight container in the refrigerator for up to one week.