Put the potatoes in a pan of water and cook them for ten minutes. Add the peas after that and boil both of them together for five more minutes or until you are sure that they have gone tender. Drain the water and rinse the vegetables under cold water and allow to cool.
While the potatoes are boiling, make the eggs in another pan. Put the eggs in the pan and cover with water that covers them. Boil the water for 8 minutes. Drain out the hot water and put the eggs in a bowl of cold water to cool down. When they cool down, peel them and cut them into quarters length ways.
Make the dressing now. First of all open up the can of anchovy fillets. Combine them with garlic, mustard, lemon juice and olive oil in a blender. Blend well so that a smooth dressing is formed.
Toss together the potatoes and beans in a large bowl. Pour half of the dressing over them and toss well to coat. Make chunks out of the tuna. Arrange lettuce in a salad bowl. Top the lettuce with the potato and bean mixture. Next add the eggs and tomatoes. Scatter the tuna chunks and olives over the salad. In the end, drizzle half the dressing over it all and serve right away.