Whisk soy sauce, sesame oil, vinegar, sugar and garlic in a small bowl, and then stir in spring onion.
Cut tofu into 5cm squares, again cutting in half horizontally to form 2cm-thick slices. Place flour in a shallow dish. Working with 1 tofu piece at a time, dust with flour. Season with salt and pepper.
Heat 1cm oil in a large frying pan over medium heat. Cook tofu, in 2 batches, for 1 minute each side or until crisp and golden, then drain on paper towel.
Place tofu, overlapping, on a platter. Drizzle over half the dressing, scatter with coriander leaves and peanuts.
Serve with remaining dressing in a small bowl for dipping.