Step 1 Preheat oven to 180°C. Place beef into a large bowl with paprika and ground black pepper.Toss to coat. Spray a frying pan with oil and place over high heat. Add half the beef. Cook, stirring constantly, for 3–4 minutes, until browned. Transfer beef to a casserole dish. Repeat with remaining beef.
Step 2 Add onions, capsicums, celery, thyme and caraway seeds (if using) to the same frying pan, plus 2 tablespoons cold water. Reduce heat and cook gently for 5 minutes, until softened. Add to casserole dish.
Step 3 Combine stock with tomato paste and pour over beef and vegetables. Bring to the boil over high heat, cover and transfer to oven. Cook for 1 1/2–2 hours, until sauce is thick and beef is tender. Check after 1 hour and, if sauce needs thickening, remove lid for final 30 minutes of cooking.
Step 4 Twenty minutes before serving, place potatoes into a saucepan of cold water. Bring to the boil and cook for 15 minutes, until tender. Drain well and return to saucepan. Mash with a masher and stir in milk, mustard and pepper. Serve goulash with mash and steamed green vegetables.