Prepare the tomato-cucumber salad by combining the tomatoes, onion, cucumber, olives, feta cheese, and lime juice in a large bowl. Season with a little salt and black pepper, to taste, and stir to combine. Set aside.
Lemon Garlic Pan Sauce
Heat the olive oil and garlic in a large cast-iron skillet over medium heat. Add the lemon and capers and sauté until the lemon softens and develops a bit of color, approximately 2 minutes.
If the fillets have excess moisture, blot them dry with paper towels. Next, add the fresh mahi mahi fillets to the hot pan with the lemon garlic mixture and generously season the first side with salt and black pepper. Cook for 3-4 minutes, flip and season the second side. Continue to cook until the fillets are cooked through, and they flake easily with a fork.
Putting it all together
Remove from heat and add the tomato-cucumber mixture to the hot skillet. Cover for 1-2 minutes, or just until the cheese is softened, and the other ingredients are warmed through. To serve, top each piece of fish with fresh thyme sprigs, fresh lemon zest and offer the lemon wedges on the side. Enjoy!