Sicilian Rice Balls (Arancini)

Name: Sicilian Rice Balls (Arancini)
Prep time: 1 h
Cook time: 3 h 5 min
Total time: 3 h 5 min
Yield: 18 pieces
Ingredients: 1200 g water; 1 tsp fine sea salt; 400 g risotto rice; 25 g unsalted butter; 80 g Parmesan cheese, grated; 1 medium egg; 1 pinch saffron powder; 40 g onion; 30 g olive oil; 100 g beef mince; 200 g tinned chopped tomatoes; 30 g fresh mushrooms; 1 Tbsp tomato purée; ½ tsp fine sea salt; 1 pinch ground black pepper; 70 g frozen green peas; 2 medium eggs; 300 g mozzarella; 100 - 150 g breadcrumbs; oil