1) Add the potatoes to a large pot and cover by 2.5cms with cold water. Add 1 tbsp of salt and bring to a boil over high heat. Cook until fork tender, 12 to 15 minutes and drain well.
2) Let cool slightly then slice into 1cm thick pieces and add to a large serving bowl.
3) Stir together the remaining ingredients in a medium bowl. Pour the mixture over the warm potatoes and mix gently until combined, mashing the potatoes slightly.
4) Season again with salt and pepper, to taste, before serving.