Heat a frying pan over medium-high heat. Add the chorizo. Cook, stirring, for 5 mins or until golden brown. Use a slotted spoon to transfer to a slow cooker.
Add onion, combined capsicum and celery to the pan. Cook, stirring, for 5 mins or until onion softens. Add the cumin, ground coriander, paprika, oregano and garlic powder. Cook, stirring, for 1 min or until fragrant. Transfer to the slow cooker.
Add pork to the pan. Cook, turning occasionally, for 5 mins or until brown all over. Transfer to the slow cooker. Add the tomato. Cook for 3-4 hours on high (or 6-7 hours on low).
Add the corn kernels and black beans to the pork mixture. Cook for a further 15 mins or until heated through.
Meanwhile, to make the dirty rice, melt the butter in a medium saucepan over medium heat. Add the onion. Cook, stirring, for 5 mins or until softened. Add the chilli powder and turmeric. Cook for 30 secs or until fragrant. Add the rice. Stir to coat. Add the stock. Bring to the boil. Reduce heat to low. Cook, covered, for 12 mins or until rice is tender and liquid is absorbed. Set aside, covered, for 5 mins to rest. Add the spring onion and coriander. Toss to combine.
Divide rice among serving bowls. Top with pork stew. Sprinkle with coriander leaves. Serve with lemon wedges.