In this recipe, salt does double duty: Not only does it give the potatoes their salty taste, but it also gives them their creamy texture.
There’s a lot more salt dissolved in the super-salty boiling water than there is in the raw potatoes. So, as the spuds cook, some of that dissolved salt moves from the water into the potatoes, seasoning them all the way through. (Thanks, diffusion!)
The salt also breaks down pectin in the potatoes (pectin is like a glue that holds the potatoes’ cells together). As the pectin breaks down, the cells inside the potatoes start to separate. At the same time, lots of tiny starch granules in the potatoes’ cells absorb water and swell up (think: teeny sponges), giving the potato a creamy (and smashable!) texture.
Salt-and-Vinegar Smashed Potatoes
- 2 quarts water
- 1 1/4 cups salt
- 2 pounds small red potatoes
- Vegetable oil spray
- 1/4 cup extra-virgin olive oil
- 3 tablespoons malt vinegar
- 1/4 teaspoon pepper
Adjust oven rack to the upper-middle position and heat oven to 450 degrees F. Set a cooling rack inside one rimmed baking sheet.
Add water to a large pot and bring to boil over medium-high heat. Add salt to water and stir with slotted spoon until dissolved. Add potatoes to pot. Cook potatoes until very tender and a paring knife slips in and out easily, 20 to 30 minutes.
Use a slotted spoon to transfer potatoes to the cooling rack set in the baking sheet. Let potatoes sit to dry out for 10 minutes.
Meanwhile, spray a second rimmed baking sheet with vegetable oil spray. Use a pastry brush to evenly coat the baking sheet with olive oil.
When potatoes are dry, transfer potatoes to the oiled baking sheet. Use a 1-cup dry measuring cup to press down on each potato to flatten until 1/2-inch thick.
Use a clean pastry brush to paint potatoes with half of the vinegar. Sprinkle potatoes with pepper.
Roast until potatoes are well browned and crisp, 30 to 35 minutes. Transfer baking sheet to cooling rack. Use a pastry brush to carefully paint potatoes with the remaining vinegar. Serve.
Use small red potatoes, measuring 1 to 2 inches in diameter.
If you prefer to use kosher salt, you will need 1 3/4 cups of Morton kosher salt or 2 1/2 cups of Diamond Crystal.