Heat the air fryer to 180°C. Toss the pumpkin wedges with a little oil, massaging it in to coat, then add them to the air fryer basket in a single layer and cook for 15-20 minutes, turning halfway, until crisp at the edges and fudgy soft inside.
Meanwhile, pour the butter beans and their liquid into a small saucepan. Add half the drained chickpeas and all the miso, then bring to a simmer over a medium heat. Cook for 5 minutes, then use a stick blender to whizz to a smooth purée. Season to taste with salt and pepper, then keep warm over a very low heat.
Once the pumpkin is ready, transfer it to a plate. Put the remaining chickpeas, the pumpkin seeds and sage leaves in a bowl and dress with a splash of veg oil. Spread the mixture out in the air fryer and cook for 5 minutes until crisp and golden.
Spread the bean purée over a serving platter and arrange the pumpkin wedges on top. Sprinkle with the crispy chickpeas, pumpkin seeds and sage leaves. Finish with some sumac, a drizzle of olive oil, sea salt and black pepper, then serve.