Boil the potatoes and cut into bite-sized pieces. Crush the garlic and finely chop the herbs. Rinse and chop the herrings.
While the potatoes are still warm, mix with the garlic, herbs, olive oil, lemon juice and zest. Leave covered for 10 minutes. Taste and add more oil or lemon juice as required. Season to taste, remembering that the herring has been in salted water. Add the herring to the mix and serve in a large bowl.