Preheat the oven to 200°C/fan 180°C/gas mark 6. Put the peppers in a large roasting tray and drizzle with 1 tbsp olive oil. Roast in the oven for 25-30 minutes, or until the peppers start to blister. Remove from the oven and place in a bowl. Cover with clingfilm and leave to cool.
Heat another 1 tbsp oil in a large frying pan over a medium heat. Add the sausages and cook for 12-15 minutes, turning frequently, until the sausages are golden.
Meanwhile, heat the remaining oil in a large saucepan. Add the garlic and cook for a couple of minutes, until the garlic releases its aroma but hasn't coloured. Add the beans and cook for a further 4-5 minutes, until the beans are warmed through. Add the hot stock, then roughly mash the beans using a potato masher. Season with black pepper, then stir through the oregano. Keep warm.
Remove the seeds and skins from the peppers and cut into thin strips. Toss the peppers with the capers and serve with the sausages and mash.