1 small Yukon gold potato, peeled and quartered
1 1/2 tsp. kosher salt
3 garlic cloves, finely chopped
1 Tbsp. Dijon mustard
1 large egg yolk
1/4 tsp. freshly ground pepper
2/3 cup extra-virgin olive oil
1 Tbsp. fresh lemon juice
To make aioli: In a stockpot, place potato and enough cold water to cover; bring to boil. Add 1 teaspoon salt and cook until tender, about 15 minutes. Drain.
In a food processor, blend potato, garlic, mustard, egg yolk, remaining 1/2 teaspoon salt, and pepper. With machine running, gradually add oil in a slow, steady stream until thick and blended. Add lemon juice; transfer to serving bowl.