Boil the potatoes in their skins until they are tender when pierced with a sharp knife, about 30 minutes. Prepare dressing by beating together olive oil, wine vinegar, garlic, basil puree or fresh basil, salt and pepper.
Combine the green pepper and onion with the dressing in a large bowl. Drain potatoes as soon as they are done. When they are cool enough to handle, slice them and add to green pepper and onion, tossing gently while still warm. Refrigerate for several hours or overnight for flavors to blend. Serve at room temperature.
