Soft polenta with tomato sauce

Method

1. Sauce: chop the onion and garlic and dice the tomatoes. In a pan over medium heat, warm the olive oil and soften the onion with a pinch of salt for 4 minutes; add the garlic for 1 minute and the tomato for 6 minutes until it breaks down.
2. Add the passata and 100 ml of water, season with salt and pepper and simmer over low heat, half covered, for 20 minutes, stirring now and then. Stir in the chopped parsley at the end.
3. Polenta: meanwhile, in a bowl, whisk the cornmeal (fubá) into 500 ml of cold water until there are no lumps.
4. In a large pan, bring 1 L of water to the boil with the stock cube. Lower to medium heat and pour in the cornmeal mixture gradually, whisking constantly.
5. When it thickens, turn the heat to the lowest and cook for 20 to 25 minutes, stirring with a wooden spoon every 2 minutes and scraping the bottom (it spits: use a long-handled spoon), until creamy with no raw-flour taste. If it gets too thick, add hot water a little at a time; it should slide slowly off the spoon.
6. Turn off the heat, stir in the butter and half the parmesan and taste for salt. Serve at once in deep plates, with the sauce on top and the remaining parmesan.