Scrub each potato under running water with a brush or rough sponge. Dry thoroughly — dry skin crisps instead of steaming. Poke all over with a fork or knife about 8 times per potato to let steam escape and heat the center evenly. Optionally rub skins with olive oil, salt, and pepper for extra flavor and crispiness. Line a baking sheet with foil or parchment, place potatoes on the sheet with space between them.

Preheat oven to 425°F and let it fully come to temperature. Place sweet potatoes on a baking sheet on the center rack. Bake 45–70 minutes: medium potatoes (5–6 oz) take 45–50 minutes, larger ones 60–70 minutes. At 30 minutes, rotate the pan 180°. Start checking doneness at 45 minutes. Some caramelized drips on the pan are normal at this temp.

Fork test: insert a fork or thin knife into the thickest part — no resistance means it's done. Or squeeze gently through an oven mitt; it should feel soft and yield easily. If still firm at the center, return to the oven for 5–10 more minutes and test again. Remove from oven, rest 5 minutes. Split the top lengthwise, press the ends to open and fluff. Season with salt and pepper, then add toppings of your choice. Don't pull early — trust the fork test over how the skin looks.