Preheat the oven to 190°C (Gas Mark 5). Toss the pumpkin wedges with 1 tablespoon of the oil in the oven bag. Make a slit in each shallot and garlic and tuck into the bag together with the rosemary. Put the bag on a roasting tin and toast for 20-25 minutes. Take the oven bag out of the oven and carefully give everything a shake. Return to the oven for another 15-20 minutes. Discard the rosemary and, when cool enough, peel the shallots and garlic cloves, discarding the skins. 

Transfer the contents of the bag into a saucepan, with all the remaining juices and spice mix. To the vegetables, add the sherry, tomatoes and tomato paste, and keep stirring. Add the stock and all but a small handful of sweetcorn to the pan. Bring to a simmer. Reduce heat so that the liquid bubbles gently, half cover with a lid and leave to simmer for 15-20 minutes. 

Blend everything in the pan with a hand blender. Once smooth, add a squeeze of lime juice, check for seasoning and adjust accordingly. Serve in bowls, topped with the reserved raw sweetcorn, sliced chili, crumbled feta and the coriander leaves.