Bring the water to a boil in a large pot. Once boiling, add salt and oil. Reduce heat to low.
Add the cornmeal in smaller batches while stirring constantly. If you add the cornmeal at once or even in larger batches, your polenta easily becomes lumpy.
Cook the polenta for 50 minutes, stirring almost constantly.You don’t have to stir it literally constantly, but make sure you stir it every minute to prevent it from burning or sticking to the bottom of your pot.
Pour the cooked polenta onto a large cutting board and let it cool and solidify for 10 minutes.
Optional: Cut it in 3/8 inch (1 cm) slices and fry them over 1-2 tablespoons of oil in a large pan over high heat for 3-5 minutes on each side, until you get the desired color.To slice polenta, you can use a sharp thin blade knife. But the traditional method in several places is to use sewing cotton thread. You take about a foot long piece (30-35 cm), twist one end on a finger of your left hand, the other end on a finger of your right hand. Then you can use the thread as a knife to cut the slices. If needed, use light right-and-left motion while cutting.