Northern Italy — the Veneto, Lombardy, Friuli, and Piedmont. Maize was introduced to these regions from the New World in the 16th century via Venice's trade routes. Within 50 years it had displaced other grains as the primary food of the northern Italian agricultural poor.
Polenta is the principal cooked grain preparation of northern Italy — from the Veneto through Lombardy, Piedmont, Trentino, and Friuli-Venezia Giulia. Made from dried, ground maize (corn), cooked in salted water with continuous stirring for 40-50 minutes until thick, creamy, and fully cooked, then dressed with butter and Parmigiano, or allowed to set and then grilled or fried. The key variables are the grind (coarse, medium, or fine), the variety (white or yellow maize), and the liquid ratio — and these determine both texture and regional character.
Well-made polenta has a sweet, nutty corn flavour that complements braised meats, sauced fish, and aged cheeses. Yellow maize is more corn-forward and robust; white is more delicate and neutral. The butter-and-Parmigiano finish provides the fat and salt that carry and amplify the corn's natural sweetness. Grilled polenta develops a Maillard crust with a bitterness that balances the fat.
The ratio of water to polenta is typically 4:1 by volume for a medium-consistency polenta — more water produces a pourable polenta; less produces a firm one. Bring well-salted water to a full rolling boil before adding polenta in a thin stream, whisking constantly to prevent lumps. Reduce heat to the lowest possible simmer and stir with a long-handled wooden spoon or whisk every 2-3 minutes. The polenta is cooked when it begins to pull away from the sides of the pot (usually 40-45 minutes for regular polenta, 20-25 minutes for bramata or coarse, longer for the most traditional versions). Finish with cold butter and Parmigiano off heat. White polenta (from white maize — Veneto tradition) is milder and more delicate than yellow; bramata (coarsely ground) is the Piedmontese preference.
Traditional Venetian and Piedmontese polenta is made in a copper pot (paiolo) with a flat-bottomed wooden stick — the copper distributes heat more evenly. For a restaurant service, polenta can be made in advance, spread onto trays to set, and then grilled or fried to order. Set polenta cut into pieces and grilled over charcoal is one of the best things to serve with braised meats — the char adds a bitterness that complements the richness of the braise.
Adding polenta to cold water — lumps form that cannot be worked out. Under-cooking — raw polenta has a starchy, grainy taste and will continue to thicken after service. Stopping stirring entirely — polenta sticks and burns within minutes on the bottom. Adding all the polenta at once — lumps; always add in a thin stream while whisking.
Marcella Hazan, Essentials of Classic Italian Cooking; Giorgio Locatelli, Made in Italy