DIY Loaded Jacket Potatoes

• 500 g lean beef mince
• 1 brown onion, diced
• 800 g tin diced tomatoes
• 1 tsp oregano, dried
• 4 large white potatoes
• 1 cup corn kernels, frozen
• 0.25 cup spring onions, finely chopped
• 2 medium carrots, grated
• 0.5 cup light sour cream