Preheat the oven to 240°C.
Fill a large pot with water and heat it over high heat until boiling. Add the salt, bicarbonate of soda and potatoes. Stir.
Return to the boil, then reduce to a simmer, and cook until a knife meets little resistance when inserted into a potato chunk, about 10-15 minutes.
Drain the potatoes and rest them in the pot for 1 minute to allow excess moisture to evaporate.
Drizzle the potatoes with the oil and season with the Roast vegetable Salt. Toss to coat, shaking the pot roughly, until a layer of mashed potato–like texture has built up on the potato chunks.
Transfer the potatoes to a large baking sheet and spread them out evenly.
Roast on the middle shelf of the oven without moving them for 20 minutes.
Turn the potatoes and continue roasting them for 30 minutes, or until they are deep brown and crisp all over. Open the oven door every now and then to release steam.
