Wash the potatoes very well and scrub their skins. Slice them into rounds about 3/4 inch (2 cm) thick. Bring salted water to a boil, add the potatoes and carrots, and cook for about 8–10 minutes, until tender.

Prepare the dressing. In a bowl, combine salt, pepper, vinegar, lemon juice, and a little water, and mix well. Add the mustard and stir. Gradually whisk in the olive oil until the vinaigrette thickens. Add the green onions, dill, and parsley, and mix well.

Once the potatoes are tender, carefully drain them in a colander so they don't break apart. Spread them out in a baking dish and pour the vinaigrette over them. Let them cool without stirring so they don't fall apart.

After they have cooled, transfer the potatoes to a salad bowl and garnish with the pepper strips.