Preheat the oven to 180C/350F/Gas 4.
Cut around the stalks and remove the very tops off the peppers. Put these to one side. Remove the insides and seeds of the peppers.
Heat the olive oil in a frying pan and sauté the peas with the red onion and garlic.
Soak the bread in water for two minutes, then break it into breadcrumbs. Add the breadcrumbs and the egg to the pea mixture and stir.
Stuff the emptied peppers with the mixture and replace their tops. Place in a baking tray and season with salt and freshly ground black pepper, and drizzle with olive oil.
Cook them in the oven for about 20-30 minutes until soft and cooked through.