- 1 large egg at room temperature
- 1 tablespoon Dijon mustard
- 1 tablespoon red or white wine vinegar
- ¼ teaspoon kosher salt, or more to taste
- ½ cup extra virgin olive oil
- ½ cup butter
- 1 teaspoon fresh lemon juice, optional
- Melt the butter and let it cool down to room temperature before adding.*
- Add egg to the small bowl of a food processor and process for 20 seconds.**
- Add the mustard, vinegar, and salt. Process for another 20 seconds.
- With the processor on a low speed, add the oil in a very thin stream (this is critical for proper emulsification).
- When all of the oil has been added, scrape the bottom and sides of the bowl and process for an extra 10 seconds. Taste mayonnaise for seasoning, then add salt, lemon juice or extra vinegar to taste.
- If the mayonnaise seems too thin, very slowly add more oil with the processor running until the mixture has thickened.
*If using salted butter, don’t add extra salt.
**If you only have a large food processor, use an immersion blender or emulsify the mixture by hand.