Tilapia with Green Tomato Tapenade

Name: Tilapia with Green Tomato Tapenade
Ingredients: 1 teaspoon olive oil; 0.25 large onion, diced; 1 (10 ounce) can diced tomatoes with green chile peppers (such as RO*TEL®); 2 green tomatoes, diced; 1 tablespoon capers; 1 pinch dried basil; salt and ground black pepper to taste; 1.5 pounds tilapia fillets; 1 tablespoon olive oil; 1 tablespoon lemon juice