Arancini scotch eggs

Name: Arancini scotch eggs
Ingredients: 1 tbsp sunflower oil, plus extra for deep-frying; 1 onion, finely chopped; 50g pancetta or smoked streaky bacon, finely chopped; 2 garlic cloves, crushed; 200g arborio rice; 100ml white wine; 600ml hot chicken or vegetable stock; 50g parmesan, grated; 15g cold salted butter; 1 tsp cream of tartar (optional); 4 fridge-cold eggs, plus 1 beaten egg; 1 tsp milk; 100g panko breadcrumbs; 50g plain flour; dressed salad, to serve (optional)