Before baking, preheat oven to 325°F / 160°C /Gas Mark 3
Trim excess fat from beef and cook with onion and garlic in 3 tablespoons of oil until meat is browned. Add tomatoes, green pepper, salt, pepper, sugar, apricots, white potatoes, sweet potatoes and broth. Cover and simmer 1 hour.
Meanwhile, cut top off pumpkin and discard. Scoop out seeds and stringy membrane. Brush inside of pumpkin with remaining oil and sprinkle lightly with salt and pepper.
Stir sherry and corn into stew and spoon into pumpkin shell. Place shell in shallow pan and bake at 325°F for 1 hour, or until pumpkin meat is tender.
Place pumpkin in large bowl and ladle out stew, scooping out some of pumpkin with each stew serving.