To prepare the artichokes; Squeeze the lemon into a bowl of cold water. Trim the artichoke stem leaving about 7cm attached to the flower. Use a potato peeler too peel the outer layer of the stem. Cut 2cm off the top of the artichoke. Peel and discard 3-4 layers of the outer leaves, so the pale yellow-green leaves are exposed. Cut artichokes in half lengthways. Use a small teaspoon to remove and discard the choke (furry part). Put the artichoke in the bowl of water to stop it browning. Repeat with remaining artichokes.
To cook the artichokes; Bring a large saucepan of salted water to the boil. Drain artichokes and add to the pan. Use an upturned plate to place over artichokes to hold them down under the water. Simmer for 15-20 minutes or until tender. Carefully transfer to a large plate.
Meanwhile, for the parsley crumbs, heat oil in a frying pan over medium-high heat. Add breadcrumbs, cook, stirring until light golden. Transfer to a bowl, stir in parsley.
Wipe the pan clean, whisk all the vinaigrette ingredients together with salt and pepper. Pour into warm pan and shake over low heat until warm. Pour the dressing over the warm artichokes. Scatter over the crumbs and serve.