Steak and kidney pudding

Name: Steak and kidney pudding
Prep time: 30 min
Cook time: 3 h 45 min
Total time: 3 h 45 min
Yield: 6 portions
Ingredients: 200 g plain flour; 100 g suet mix; 5 sprigs fresh thyme; 1 tsp mustard powder; ¼ tsp salt; ¼ tsp ground black pepper; 120 g cold water; 20 g oil; 1 brown onion; 600 g gravy beef; 200 g lamb kidneys; 2 carrots; 1 tbsp plain flour; 1 tbsp tomato paste; 2 tbsp Worcestershire sauce; 1 tbsp Vegetable stock paste; 100 g water; ½ tsp salt; ½ tsp ground black pepper; 200 g fresh mushrooms; butter; 2200 g water