Whisk together vinegar, mustard, anchovy paste. Pour olive oil in thin stream, give a good emulsion. Add olives, garlic and shallots. Season with salt and pepper to taste. Add a dash of oregano if desired. This dressing can be made in advanced. Refrigerate for up to a week.
Use the best summer tomatoes available such as Beefsteak, purple Cherokee, Brandywine, Better Boy, Grape etc... Add some cherry tomatoes (skin on) for garnishing if desired. Cut a light “X” on the bottom of each tomato, boil them briefly, and dunk them in ice water. Remove stems and peel; set aside. Place potatoes in a saucepan, add a dash of salt, and cover with water. Bring to a boil and cook for about 25 minutes or until fork tender. Drain and let cool for 10 min prior to peel. Drain cod liver and save oil. Cod liver is rich in vitamine A & D, and omega-3 fatty acids. Use some for the salad and save leftover cod liver oil for later use.
Slice out tomatoes and potatoes. Save some potatoes and dice out, and mix with cod liver. Cod liver can also be added on top of the salad as is. Add chopped chives if desired. Arrange tomato and potato slices on plates, and season with salt and pepper. Top with the cod liver mixture and season generously with the dressing. Garnish with fresh herbs. Enjoy!