For the polenta
350 g (12 oz) bramata polenta
1.75–2 litres (3–3.1/2 pints) water
Maldon salt and freshly ground black pepper
olive oil
For the sauce
3 tablespoons olive oil
4 medium red onions, peeled and sliced as thinly as possible into rounds
2 garlic cloves, peeled and cut into slivers
2 × 800 g (1.3/4 lb) tins peeled plum tomatoes, drained of their juices
Maldon salt and freshly ground black pepper
extra virgin olive oil
1 bunch rocket leaves
For six
Make the polenta as described here, omitting the butter and Parmesan. When ready, transfer to a large, flat baking tray or plate, and spread out to set.
To make the sauce, heat the oil in a large saucepan or frying pan then add the onions. Reduce the heat and cook the onions until they are very soft. The onions must disappear into the tomato sauce. This will take at least 40 minutes. Some 5 minutes before the end of cooking, add the garlic.
Now add the tomatoes and stir to break them up. Season with salt and pepper and cook slowly, stirring occasionally, for at least 1.1/2 hours. The oil should come to the surface and the sauce will be dark red and extremely thick, with no juice at all.
Preheat the grill or griddle pan. Cut the polenta into individual wedge-shaped slices. Brush lightly with olive oil. Season each side of each slice generously with salt and pepper. Place on the hot grill, turn over when brown and crisp and repeat on the other side.
Serve with the sauce, extra virgin olive oil and a few leaves of rocket.