- ½ cup olive oil
- ½ cup grapeseed oil
- 1 large egg yolk at room temperature
- kosher salt
- 1 teaspoon white or white wine vinegar
- Combine the olive oil and grapeseed oil in a bowl and set aside. Whisk the egg yolk, vinegar and ½ teaspoon salt in a small additional bowl.
- With an immersion blender, drizzle the oil mixture into the yolk mixture (you can do this whisking vigorously by hand too), until thick and smooth. Keep refrigerated.