Sprinkle diced lamb with ¼ tsp salt. Place a large pot or casserole dish over medium-high heat and drizzle in half the olive oil. Add half the lamb and cook for 4–5 mins until meat is golden. Transfer browned lamb to a plate, and repeat with remaining lamb and oil.
Return all meat and any resting juices to the pot. Add onion, garlic, and carrots, and cook a further 3–4 mins, until onion begins to soften.
Stir through paprika. Add water and bring to the boil, then cover pan, reduce heat to low, and simmer for 2 hours.
After 2 hours, remove lid, add butter and stock, and return to the boil. Scatter rice over the liquid and gently stir to submerge.
Replace cover, return heat to low and simmer a further 30 mins, until rice is cooked and lamb very is tender.
Remove pan from heat, add spinach, and replace cover. Set aside for 10 mins to wilt spinach leaves. Serve casserole with parsley, lemon wedges, and a fresh green salad.
Instead of simmering on the stove, preheat oven to 180°C, and bake the casserole from Step 3. All other steps remain the same.