This 40 minute video will change how you think about Potatoes.

Sweet potatoes contain amylase, an enzyme activated above 135F and active to around 170F, which breaks starch down into maltose and glucose.

Slow cooking a sweet potato at about 200F in the oven gives the enzyme more time to convert starch to sugar than a hotter, shorter cook.

One solution for crispy sweet potato fries is to add a potato starch slurry to boiled sweet potatoes before frying them.

When starches are heated with a liquid such as the water inside the potato they absorb moisture and swell, a process called gelation; potatoes hold onto that water instead of losing it.

Taste test: sous vide potatoes with no salt added, tasted with the nose plugged. Plain, they taste almost identical and very neutral, the sweet potato excepted, and even that is less sweet than expected.

Roasted test: parboil each variety briefly in salted boiling water, drizzle a little oil over the top and cook in the air fryer until browned.

Texture by cut: slice extremely thin and fry for a crisp chip; cut thicker and kettle fry for crunch; steam for tender; boil and mash with butter and milk for creamy; cut into sticks and fry for crisp and airy; cut into bigger chunks and roast for crisp and creamy.

Mashed test: skin and boil 150 grams of each potato in salted water until tender, then add 15 grams of butter to each. Milk and cream were left out to keep the variable single.

French fry test: chop each variety into sticks, boil in salted water, then double fry on the stove.

Chip test: slice each variety thinly on the mandolin, wash in salted water, dry, then add directly to the oil.

His preferences: russets for french fries, Yukon Gold for mashed, fingerlings for roasting and confit, red potatoes boiled with butter and parsley, coloured potatoes for visual interest.