1.Preheat Oven To 450?. 2.Cut The Celeriac Into 1/4" Strips (Like French Fries) And Place Them In An Oven-Proof Dish. Drizzle With Olive Oil And Season With Sea Salt And Freshly Ground Black Pepper If Desired. 3.Bake The Fries For Approximately 10 Minutes. 4.Meanwhile, Place The Fish In Another Oven-Proof Dish And Season With Sea Salt, Freshly Ground Black Pepper And The Juice Of 1 Lemon. 5.After The Celeriac Has Baked For 10 Minutes, Decrease The Temperature To 400 And Bake The Fish Together With The Fries For Another 8-10 Minutes. 6.While The Fish Bakes, Combine The Arugula, Olives, Capers, And Garlic In A Food Processor And Chop Until It Resembles A Tapenade. 7.Serve The Tapenade On Top Of The Cod, With The Celeriac Fries On The Side.