Turn your oven to 250C (480F). Trim the base of the cauliflower so it sits flat and will fit into your pot or a small roasting tray - you want the cauliflower to bit snugly so you don't loose too much water to evaporation. Discard any rough leaves but keep a few of the inner ones.
Place in said pot. Add water to pot - enough to cover the base by about 2cm (1in). Sprinkle over the salt.
Roast uncovered for 60 minutes until the cauliflower is deeply browned. Top up the water. Cover with the lid of your pot or foil.
Roast covered for another 60 minutes or until the cauli is so soft you can cut into it with a spoon.
Discard the water and serve cauli hot as a side dish. I also like to pop the leftovers in the fridge and pull them out and serve at room temperature anywhere you want some cooked veggies.