1. Place the block of tofu between sheets of kitchen paper towels. Cover with a heavy object (a cutting board, a dish filled with water, etc.) and press for 15 minutes.
2. Meanwhile, combine the water, soy sauce, mirin and dashi. Bring to the boil over medium heat. Remove from heat and set aside.
3. Remove the kitchen paper and cut the tofu into 1 to 2cm cubes. Lightly coat the cubed tofu in flour.
4. Heat the oil for deep frying. Fry the tofu for 4 to 6 minutes, or until golden brown. Fry in batches if needed, so as not to overcrowd the pan.
5. Place the fried tofu in a serving dish then pour over the sauce and sprinkle with spring onion. Enjoy!