Crush spice blend in a mortar and toast in a frying pan until aromatic.
Blend ginger, garlic, onion, chillies, turmeric, spices, tamarind, vinegar, oil, sugar, and salt into a fine paste.
Rub some masala paste into the pork and marinate in the fridge for several hours.
Preheat the oven to 170°C.
Mix pumpkin, potatoes, and extra onions into the remaining masala paste.
Heat oil in a deep roasting tray on the hob.
Brown the marinated pork in the roasting tray after scraping off excess masala.
Surround the pork with marinated vegetables and seal the tray tightly with foil.
Bake at 170°C for 30 minutes, then reduce to 130°C and cook for 3-4 hours.
Soak coleslaw vegetables in water, keeping beetroot separate to avoid staining.
Whisk together garlic, mayonnaise, mustard, chilli, and coriander to make the dressing.
Drain vegetables and toss with the dressing just before serving.
Shred the pork with a fork and serve with the roasted vegetables and coleslaw.