Preheat the oven to 350°F (175°C).
Scrub the potatoes under cold running water with a stiff brush, then pat them dry.
Poke each potato 8–12 times all over with a fork to allow steam to escape while baking.
In a large bowl, toss the potatoes with 2–3 tablespoons olive oil until lightly coated, then sprinkle evenly with kosher salt to taste.
Place the potatoes directly on the oven's middle rack or on an aluminum foil–lined baking sheet and bake for about 1 hour, until the skins are crisp and a fork inserts easily.
Let the potatoes cool briefly until they can be handled, make a dotted line lengthwise with a fork, then squeeze the ends to open them; serve with desired toppings.