Cut stems of artichokes so they are 1 inch from the base, you can also use scissors to cut the thorns. Boil 5 cups of water in a very large pot. Once the water is boiling, place the artichokes and two cloves of peeled garlic in the pot. Boil for 25 minutes, rotating artichokes occasionally. Remove and drain the artichokes. Once cooled, cut the artichokes in half and brush with olive oil. Place on the grill, cut side down, over medium flame for about 10 minutes. Remove artichokes and garnish with orange zest and capers. Serve with garlic butter dipping sauce.