Adjust oven rack to centre position and preheat oven to 240°C.
Bring a large pot of water to the boil. Add kosher salt, baking soda, and potatoes and stir.
Return to a boil, reduce to a simmer, and cook until a knife meets little resistance when inserted into a potato chunk, about 10-15 minutes after returning to a boil.
Drain the potatoes and rest them in the pot for 1 minute to allow excess moisture to evaporate.
Drizzle the potatoes with olive oil and season with Garlic Lovers' Spice. Toss to coat, shaking pot roughly, until a layer of mashed potato–like paste has built up on the potato chunks.
Transfer potatoes to a large baking sheet and spread them out evenly. Roast without moving them for 20 minutes.
Turn potatoes and continue roasting for 30 minutes until potatoes are deep brown and crisp all over, opening the oven door every now and then to release steam. Season with salt and serve immediately.
