Gather all ingredients.

Bring water, potatoes, and 2 tablespoons salt to a boil in a large Dutch oven or medium pot over high heat. Reduce heat to medium-high and cook, stirring occasionally, until potatoes are just fork-tender, about 6 to 8 minutes.

Drain potatoes and place them in a large bowl; gently toss with butter and remaining 1 teaspoon salt. Refrigerate, uncovered, until completely cool, about 45 minutes.

Stir together mayonnaise, buttermilk, chili sauce, Sriracha, and rice vinegar in a medium bowl until combined.