Heat the olive oil in a large skillet. Drain the artichoke hearts and pat dry. Halve the hearts crosswise and slice 1/3 inch thick. Add the artichokes, garlic, oregano, bay leaves and lemon zest to the skillet and cook over moderately high heat, stirring, until the herbs are fragrant, about 2 minutes. Add 1 cup of the water. Reduce the heat to moderate, cover and cook until the artichokes are tender, about 10 minutes. Discard the lemon zest, oregano sprigs and bay leaves. Stir in the lemon juice and season with salt and pepper. Transfer the artichokes and their liquid to a large bowl. Wipe out the skillet.