Thinly slice the onion, then cut the peppers into thin strips. Cut the chorizo into 2-3cm thick chunks.
Boil the pasta according to the packaging instructions, drain and keep warm under cover.
While the pasta is cooking, heat the oil in a frying pan and cook the chorizo pieces for 2-3 minutes, until they release their fat, then add the pepper and onion. Cook on low temperature for about 5 minutes.
When the vegetables are tender, add the tomato purée and chopped tomatoes, chilli flakes, vinegar, sugar and rosemary, then bring to the boil. Cook for 10 minutes then add the peas and cook for another 5 minutes.
When the sauce is thick and smooth, toss the stew with the pasta. Serve hot.