In a large nonstick skillet, heat 1 tablespoon olive oil over medium-high heat. Add the eggplant and cook, stirring, until eggplant has softened but not completely lost its shape, about 5 minutes. Remove the eggplant from skillet. Heat another tablespoon of oil in the same skillet over medium-high heat. Add the onions and cook until soft and translucent, about 5 minutes. Add the garlic and zucchini to the pan and cook, stirring occasionally, until the zucchini is soft, about 6 to 7 minutes. Return eggplant to pan and add tomatoes, herbs de Provence, 1/2 teaspoon salt and 1/4 teaspoon pepper. Simmer approximately 10 minutes. Season with additional salt, to taste. Stir in basil and remove from heat.
To cook fish, preheat broiler. Sprinkle fillets with 1/4 teaspoon salt and 1/4 teaspoon pepper. Combine the remaining tablespoon olive oil with the lemon juice and brush on fillets. Broil until fish is cooked and firm, about 7 minutes.
Mound 1 cup ratatouille on 4 plates; top each mound with 1 fish fillet and drizzle with 1/2 teaspoon herb infused oil, if using. Garnish with additional basil.