Shell the peas and broad beans and keep to one side. Blanch the artichokes whole in boiling water for 5 minutes, or until you can pull off an outer leaf with a sharp tug. They should not be completely cooked at this stage. Remove and cool. Remove the mint leaves from their stalks and chop half of them.
In a separate pan, blanch the broad beans for 2 minutes.
In a large heavy-bot