1. You could have a mixture of 250g (8.8oz) breast mince and 250g (8.8oz) thigh mince, or 100% thigh mince. I could only find breast mince so chicken fat was added to get the similar effect.
You could have just 500g of breast mince but the meatballs may be slightly dry.
2. The time taken to reduce the sauce depends on the size of the pot. The larger the diameter the faster it reduces.
3. The size of the circle made with your thumb and index finger determines the size of the ball and therefore the number of meatballs made in total. My meatball was 3-3.5cm (1¼”) in diameter.
4. Cooking time depends on the size of the meatballs. When the meatball is floating and feels light when you pick it up, it is cooked through.
5. I made tsukune on skewers as they were made when we had the family yakitori day. But you could cook individually if you like. Or two meatballs each on skewers instead of three.
6. The heat can be strong. Because tsukune is already cooked, all you need to do here is to coat with sauce and get them burnt slightly to give better flavour to them.
7. Tsukune can be frozen. After boiling, cool them down and freeze in an air tight container or freezer bag.