What is that grey ring around the yolks of boiled eggs?

What is that grey ring around the yolks of boiled eggs? N. Barling

I remember working with a photographer in Spain and he was taking these beautiful shots of a dish made with hard-boiled eggs smothered in aioli. The only trouble was, the yolks were greenish and surrounded by a grey ring. In Europe they have different, more aggressive types of salmonella and cook the bejesus out of all their eggs. It's amazing what Photoshop can fix. When you cook eggs for long times, sulphur from the white comes into contact with iron from the yolk, creating ferrous sulphide. This reaction occurs more rapidly in older eggs, as the whites have become more alkaline and this helps the reaction.

Why does miso soup start cloudy then end up with a ball of stuff suspended in the middle? G. Miller

That "stuff" is the miso, fermented ground beans or grain. The clear broth around it is dashi made from kombu or dried kelp, and bonito, which is dried, and sometimes fermented, tuna. The reason it forms those rather attractive ethereal shapes in the bowl is because of currents of hot dashi rising up the centre of the bowl, cooling, then flowing back down the edges. Here is a traditional miso haiku: Hot miso forms clouds/ever forming never rain/in a bowl of soup. Please feel free to send in your miso-inspired haiku.

What is mutton mould? C. Steel

This is a classic Edwardian-era leftovers dish of 500g of leftover baked mutton or lamb minced with ½ small onion, ⅓ cup breadcrumbs, herbs, salt and pepper, a tablespoon of chutney and the same of leftover gravy. This is mixed together with an egg and placed in a pudding bowl, pressed, covered with baking paper, tied off and steamed in simmering water for one hour. It was traditionally served with macaroni and gravy.

Letters

The mere mention of pressure cookers had readers all steamed up, with several chastising me for failing to warn other readers of the dangers of exploding pressure cookers. Others berated me for failing to mention that they are available from most Indian grocers, with J. Togno stating that he is "reliably informed that pressure cookers are the secret weapon of many an Indian wife for putting a tender curry on her table." Then A. Finch broke our hearts with this tender recollection: "My husband Lloyd, who can't boil an egg, courted me with a meal cooked in a pressure cooker in 1948 while his mother was in away in the UK. I had one on my bridal wishlist when we were married in 1950, although I was scared of them after the contents of my mother's pressure cooker hit the kitchen ceiling after Father opened hers with brute force."

Send your vexing culinary conundrums to brainfood@richardcornish.com.au or tweet to @Foodcornish