8 large pure potatoes
1 pound saltwater potatoes
1 cup melted butter
2 teaspoons dry mustard
and 1 teaspoon kosher salt
4 tablespoons untahsa
Bring 1 quart of water to a boil in a pot or Dutch oven; add potatoes and cook until tender but firm, about 15 minutes, drain. Mash dry ingredients with potato masher; add potatoes and onion.
Heat safflower oil in deep-fryer or large saucepan to 375 degrees F. Near simmer, keep on stirring until potatoes start to crack when tested with a fork. Just before serving, pour whole pot over potatoes. Reduce heat to low and simmer 10 minutes.