Place the potatoes into a pan of cold salted water. Bring to the boil then lower the heat and simmer for 15 minutes until tender. Add the peas for a couple of minutes before the end of cooking the potatoes and drain well.
Add the potatoes, peas, bacon, spring onion, gherkins, pickled onion and pepper to a large bowl.
Add the pickling juice, mint and season to taste with salt and pepper. Toss to coat and serve.