Prepare the Base: Preheat your oven to 400∘F (205∘C). In a large, 12-inch oven-safe skillet, heat 1 tablespoon of olive oil over medium heat. Add the sliced onions and cook, stirring occasionally, until softened, about 4-5 minutes. Add the halved cherry tomatoes and drained cannellini beans. Stir gently and cook for another 2 minutes. Spread the mixture evenly across the bottom of the skillet and set aside off the heat.
Set Up the Dredge: Pat the cod fillets thoroughly dry with paper towels. In a shallow bowl, whisk together the whole-wheat flour, coriander, paprika, cumin, sea salt, and black pepper. In a second shallow bowl, whisk together 4 tablespoons of the extra virgin olive oil and the fresh lemon juice.
Sear the Fish: Working one fillet at a time, dip it into the lemon-oil mixture, then press it into the flour mixture to create a light coating. Heat the final 1 tablespoon of olive oil in a separate large, non-stick skillet over medium-high heat. Carefully place the coated fillets in the hot skillet and sear for 90 seconds per side, just until a light golden crust forms. The fish will not be cooked through.
Assemble and Bake: Using a fish spatula, carefully transfer the seared cod and arrange the fillets on top of the bed of beans and vegetables in your oven-safe skillet. Add the minced garlic and lemon zest to the remaining lemon-oil mixture and stir. Drizzle this infusion evenly over all the cod fillets.
Finish in the Oven: Transfer the entire skillet to the preheated oven. Bake for 8-10 minutes, or until the cod is opaque and flakes easily with a fork.
Garnish and Serve: Remove the skillet from the oven. Let it rest for 2 minutes, then generously sprinkle with fresh parsley and the optional red pepper flakes. Serve immediately.