Wet and squeeze a cotton dish cloth.

Heat water with salt and oil in a medium/large pot, but don’t get to a boil. 

Add the flour “a fontana” (=sprinkling it over the water little at the time), whisking vigorously.

Whisk until completely amalgamated.

Cover with the dishcloth (in contact with the polenta paste), leaving a crack open.

Place the pot over the smallest of your stoves, at the minimum heat, and cook 30-40 minutes.

Remove the cloth and check the consistency. If you’d like it creamier, add hot water until you get the result you are looking for (I added half a cup).