1. Heat the oil in a large pot and stir-fry the onion until fragrant. Add the leeks and stir-fry until soft. Add a third of the bacon and stir-fry for 5 minutes.
2. Add the stock and bring to the boil.
3. Drain the peas and add to the pot. Add enough hot water to cover the peas completely. Cook over medium heat for 35-45 minutes or until the peas are soft. Stir occasionally and add water as needed.