How to Make It
Puree the tomatoes in a blender. Strain the juice into a medium saucepan, pressing lightly on the solids; you should have about 2 cups. Add the onion, garlic, thyme, mint, parsley and coriander seeds and bring to a boil. Simmer over moderate heat until reduced to 1 cup, about 6 minutes. Strain the jus into a small saucepan, season with salt and pepper and keep warm.
In a large nonstick skillet, heat 1/4 cup of the olive oil. Season the zucchini with salt and pepper and cook over high heat until lightly browned and tender, about 4 minutes. Transfer the zucchini to plates. Wipe out the skillet.
Add 2 tablespoons of the olive oil to the skillet and the remaining 2 tablespoons to another large nonstick skillet. Season the fish with salt and pepper and add to the skillets, skin side down. Using a large spatula, press the fish lightly to sear the skin for a few seconds. Cook over high heat until the skin is very crisp and browned, about 5 minutes. Carefully flip the fillets and cook for 1 minute longer, until the flesh flakes when pierced with a fork. Place the fish over the zucchini, skin side up, and spoon the warm tomato jus all around. Garnish with lemon zest and serve right away.