Here's a step-by-step tutorial on how to cook artichoke hearts:

1. Rinse the artichokes and cut off the stem and top.
2. Rub the top with half a lemon and place in a pot with the lemon and some more juice if desired.
3. Fill the pot so that the artichokes are half submerged.
4. Cook for 30-45 minutes or until the heart is tender.
5. Serve with melted butter flavored to taste with lemon juice.

I hope that helps! Let me know if you have any other questions.