Preheat grill to high. Grill capsicums until skin blackens and blisters. Transfer to a plastic bag to cool, remove skins, deseed and chop.
Heat the oil in a large pan, add shallots and cook for 5 minutes until softened. Add garlic, chillies and 2 tablespoons of the stock. Cook for 5 minutes, add capsicums and sun-dried tomatoes. Cook for a further 10 minutes, add more stock if needed. Stir in capers and vinegar and cook for 1 minute.
Cook pasta in a large pan of boiling water, until al dente. Drain and toss with remaining oil. Spoon over the sauce, mix to combine. Serve hot or cold, garnished with oregano.