Lemon Vinaigrette

1/4 cup freshly squeezed lemon juice (from 1-1/2 medium lemons)
1/2 teaspoon Dijon mustard
1/2 teaspoon sea salt
1/4 teaspoon freshly ground black pepper
1/2 cup extra-virgin olive oil

In medium bowl, whisk together lemon juice, mustard, salt, and pepper. Slowly whisk in 1/4 cup olive oil. Vinaigrette can be made up to 3 hours ahead and chilled, covered. Bring to room temperature and stir before serving.