Buy your meat for steak tartare the day you plan to serve it. It should be of the best quality and very fresh. This presentation is a bit unusual and quite decorative.
Place the artichokes in a large saucepan, and add an inch of water. Bring it to a boil; then reduce the heat, cover, and simmer until the artichokes are tender, about 45 minutes. Remove them from pot and set them aside to cool.
Peel the leaves away from the artichokes, and scoop out the fuzzy choke. Reserve the bottoms.