In a large pot, bring 4 quarts of water to a boil. Also, preheat the oven to 450°F. Peel the potatoes, and then cut them into rough, 1-inch (or slightly larger) pieces.
When the water achieves a full, rolling boil, add the 2 tablespoons of salt and the baking soda. Then add the potatoes, and let them cook, uncovered, until tender when pierced with a knife -- about 10 minutes. Drain the potatoes and then return them to the still-hot pot to dry for a minute or two.
Briskly shake the pot until the potatoes develop a rough, mashed exterior. Then drizzle the potatoes with the olive oil and a sprinkling of salt and pepper. Toss with a spatula to coat. Make sure that each morsel is slick with oil.
Transfer the potatoes to a large baking sheet, spreading them out in a single layer. If possible, space the potatoes to permit air to circulate between them. Bake in the preheated oven until spotty brown on top -- about 30 minutes. Then flip the potatoes, and continue baking until the brown and crisp -- about 30 minutes.
Tip the morsels onto a serving platter, sprinkle them with salt, pepper, and the optional parsley. The potatoes will crisp further as they cool from hot to warm.