• Fill a large pot with cold water. Add the potatoes and bring them to a boil. Add the kosher salt (about 1-2 tbsp) and reduce the heat to keep the potatoes at a simmer. Cook until the potatoes are tender when pierced with a fork, about 12 minutes. Drain, sprinkle with some cider vinegar and let cool.
  
• Once the potatoes are just warm, toss them with the olives, capers, and lemon mayonnaise. Top with scallions and either serve immediately or put the salad in the refrigerator to chill.
  

Lemon Mayonnaise

• Add egg yolk, salt, mustard, and about 1-2 teaspoons of lemon juice to a bowl. Whisk together until the egg yolk is fully combined and bright yellow.
  
• Begin adding the oil, very slowly (think drops) at first and then in a thin, steady stream while whisking constantly. Once all the oil is incorporated, add more lemon juice to taste. Then mix in the lemon zest if you are using it.
• If you are happy with the lemon juice flavor, but think the mayonnaise is too thick, add water by the teaspoon until you have the texture you want.