Heat 2 tablespoons of the olive oil in large skillet on medium heat. Add onions; cook 2 to 3 minutes, stirring often until softened. Add garlic and cracked fennel seed; cook and stir 1 minute until fragrant. Add wine to deglaze, scraping browned bits from bottom of pan.
Simmer until liquid is reduced by half, about 5 minutes. Stir in tomatoes and crushed red pepper; reduce heat to low and cook 10 minutes. Add olives and cook 3 minutes longer. Turn off heat and keep warm.
Meanwhile, pat cod filets dry with paper towels. Season filets with salt and pepper, if desired. Heat remaining 1 tablespoon olive oil in large nonstick skillet on medium-high heat. Carefully place cod filets in skillet, flesh-side down (the side that had skin should be facing up). Cook, undisturbed, 2 to 3 minutes until golden-brown crust forms on bottom. Gently flip filets. Reduce heat to medium and cook 3 to 4 minutes longer or until cooked through and fish flakes easily with a fork.
Divide the Spicy Fennel & Tomato Sauce between 4 serving plates. Place cooked cod over sauce and sprinkle with parsley to serve, if desired.
Test Kitchen Tip: To crack spice seeds such as fennel, cumin and coriander, place the amount needed into a small bag. With the back of a medium size metal spoon crush or pound the seeds until desired size is reached.