Preheat a lightly greased barbecue or char-grill pan to high. Cook eggplant, turning occasionally, until lightly charred and just cooked but still holds its shape (10-12 minutes). Set aside on a wire rack. Place miso and a little water in a small bowl and whisk to form a paste. Brush paste over both sides of eggplant. Stand until cooled and ready to use.
For spicy tomato sauce, place all ingredients in a blender and blend until combined; season to taste.
For batter, place flour and sparkling water in a large bowl, and whisk until combined. Refrigerate for 1 hour to rest.
Heat a large saucepan half full with vegetable oil to 180˚C. Dip eggplant in batter, then into crumbs. Deep-fry, in batches, if necessary, until golden and crisp and eggplant is cooked (5-6 minutes). Drain on paper towel and season. Cut into 2cm-thick strips.
Divide spicy tomato sauce among plates and top with eggplant. Scatter with basil leaves and drizzle with extra olive oil to serve.
