3 tbsp white miso (if you can't find it, use 2 tbsp brown miso paste)
3 tbsp mirin
3 tbsp lime juice
Heat oven to 200C/180C fan/gas 6. Wrap the tofu in kitchen paper, place in a shallow dish and put a heavy plate on top to help squeeze out the water. When the paper is wet, replace with another wrapping and weigh down again. Chop the tofu into medium cubes (about 2.5cm). In a small bowl, mix the dressing together with a whisk.
Boil the beans for 1 min, then drain, rinse in cold water and set aside. Line a baking tray with parchment, spread out the tofu and pour over half the dressing. Sprinkle the sesame seeds on top and mix well. Bake for 20-25 mins until golden and crisp. Meanwhile, cut the sweet potatoes in half, place in a bowl, cover with cling film and microwave for 10-15 mins until very soft.
Mash the sweet potato and serve in bowls with the tofu, green beans, the dressing poured over and some spring onions sprinkled on top.