Heat 2 teaspoons oil in a pan over medium heat. Cook garlic, stirring, for 1-2 minutes until softened. Add tomatoes and balsamic, season, then cover and cook over low heat for 3-4 minutes until tomatoes soften but hold their shape. Remove pan from heat, then stir in basil.
2
Meanwhile, season fish. Heat remaining 1 tablespoon oil in a frypan over medium-high heat. Cook fish for 2 minutes each side or until golden and cooked through. Divide fish among plates, top with sauce and serve with rocket leaves.