Makes 1 1/2 cups
Put the egg, garlic, mustard, and cilantro in a blender. Cover and puree until smooth. Slowly drizzle in 1/2 cup oil through the feed tube in the top of the blender in a slow but steady stream until mixture begins to emulsify. Add lime juice and continue drizzling in remaining oil. Turn the blender off, add salt and pepper, and pulse to incorporate. Add additional lime juice to taste. Refrigerate if not using immediately.