Heat a frying pan over a high heat and toss the cuttlefish with the vegetable oil and season. Fry for 2-3 minutes or until lightly caramelised, then tip onto a plate. Reduce the heat to medium, add the olive oil and pancetta, and cook for a minute, then add the onion and cook for 10 minutes until soft, adding a little water if it colours too much. Stir in the garlic and chilli flakes, and cook for another minute. Pour in the wine and fish stock, and return the cuttlefish and any resting juices to the pan. Bring to a simmer, reduce the heat to low, cover with a lid and cook gently for 1 hour or until the cuttlefish is tender and the sauce has reduced slightly. Add the peas and heat for 2 minutes until they are just cooked.