Preheat the oven to 180°C/350°F/gas mark 4.
Blot the block of tofu on a few sheets of kitchen paper to remove any excess moisture, then cut into bite-sized chunks. Arrange the diced tofu and aubergine pieces over one large roasting tray, or two smaller trays to avoid overcrowding. Drizzle with 1 tablespoon of the sunflower oil, then roast in the oven for 20 minutes.
Meanwhile, add the remaining tablespoon of oil to a pan and throw in the ginger, garlic and chilli flakes. Cook for 2 minutes over a medium heat until fragrant.
Stir in the miso, peanut butter and maple syrup, along with 100ml (scant 1/2 cup) cold water, and simmer gently until combined, stirring frequently. Set aside.
Remove the roasting tray from the oven and pour the miso peanut sauce over the top, stirring to coat the aubergine and tofu in the sauce. Return to the oven for 5–6 minutes until the sauce is thickened and bubbling.
Remove the roasting tray from the oven and scatter with the sesame seeds and chives just before serving.