Preheat the oven to 200C/180C fan forced. Use a fork or skewer to prick sweet potatoes all over. Place on a baking tray and roast, turning once, for 50 minutes or until tender when pierced with a skewer.
Meanwhile, combine mirin, miso, soy sauce and oil in a small bowl. Lightly spray a non-stick wok with olive oil and heat over high heat. Stir-fry tofu, in 2 batches, for 2-3 minutes or until golden. Transfer to a plate. Reduce heat to medium-high and spray wok with a little more oil. Add edamame, cabbage, shallot and ginger. Stir-fry for 2 minutes or until just tender. Return tofu to the wok with half the miso mixture and stir-fry for 1 minute or until heated through.
Cut a slit in each potato. Use a fork to lightly mash flesh. Spoon filling into each potato. Top with remaining miso mixture and sesame.
Using the sweet potato, skin and all, means virtually nothing gets thrown away! Just make sure to wash it well before roasting.