Blanch the peas in boiling water. Just let the water come back to the boil and let it simmer for perhaps a minute, then drain in a large colander. Rinse the peas in cold water to stop the cooking, then let them drain until they are perfectly dry.
Line a salad bowl with the Boston lettuce leaves, using as much as you need to line your bowl.
In a separate mixing bowl, mix the drained peas and cubed ham together, then pile the mixture on top of the salad leaves.
Arrange the anchovy fillets, olives and, if using, wedges of hard boiled egg on top of the peas and ham.
Whisk together the dressing ingredients until they are perfectly emulsified. Taste and adjust for seasoning, then pour over the salad.