Prepare the instant polenta following the instructions and stir it well.
Pour out onto a small baking sheet or plate and spread to a rectangle 12 mm thick. Refrigerate until cool and set, at least 15 minutes.
In a large pot over medium heat, warm the olive oil. Add the onion and sauté until it is translucent, about 5 minutes.
Add the peas, the chopped tomatoes, couple of cups of vegetable broth and bring to a boil. Season with salt and pepper. Simmer in a covered pot for about 35 minutes. Stir from time to time, if necessary adding another cup of vegetable broth. Meanwhile, cut the polenta into slices.
Increase the heat to high and add the cuttlefish to the pot. Cover and continue to cook. Adjust the seasoning. Serve.
