In a saucepan over medium-high heat, add the olive oil and heat. Add the onion and saute until softened, about 5 minutes. Add the hot dogs and cook another 2 minutes, or until the hot dogs start to brown. Add the stock, peas, and potatoes and bring to a simmer. Simmer until the potatoes are tender, about 15 minutes. Season, to taste, with salt. Just before serving, sprinkle with fresh mint.