Prep: Preheat oven to 425 degrees F. 

Prep Fish: Place cod filets in a baking dish. Pat dry with clean paper towel. Season with kosher salt and ground black pepper.

Herb Butter: In a small bowl, combine butter, garlic, and herbs. Take herbed butter and divide between cod filets, spreading over the top of each piece. 

Bake: Place lemon slices around the cod filets in the baking dish and then move to the preheated oven, middle rack and uncovered. Let bake approx. 15-20 minutes or until the internal temperature reaches approx. 140 degrees F. (for smaller/thinner pieces this will take closer to 14-15 minutes while thicker pieces will take closer to 20-21 minutes). 

Tartar Sauce: While the cod bakes, make the Tartar Sauce: In order to remove some of the excess water from the pickles (no one wants watery tartar sauce), lay each spear on its side on a cutting board and cut off the seeds. Cut the remaining part of the pickle into small pieces and then using either a cheesecloth or clean hands, squeeze out as much remaining liquid as possible. Add prepared pickles to food processor along with mayo, dill, lemon juice, garlic, dijon, and onion. Blend until consistency is smooth (don't over-blend). Taste and adjust seasoning. 

Serve: Remove cod from oven and cool slightly. Serve with tartar sauce, rice and roasted vegetables.