Halibut @ Mercat a la Planxa By Penny Pollack August 15, 2011, 2:07 pm I’ve had a lot of good halibut this summer, but the olive oil–poached filet with its mash-up of fresh fava beans and artichokes @MercatChicago might be best of all. MERCAT A LA PLANXA: BLACKSTONE HOTEL, 638 S MICHIGAN; 312-765-0524 Tags: What Penny Eats