​I am trying to make bread, but my yeast is not working. K. Hunt

Yeast is a living thing. A single-celled fungus. It loves warm, wet environments. Think Brunswick Heads in late autumn: Constantly warm, a little bit humid. If you have never been to Brunswick Heads, then think about tinea. Tinea is a fungus. It likes the wet conditions found between the toes but not the full-on warmth of the human body. It likes the cooler extremities. About 25C is perfect for yeast to divide and conquer, turning the starch in flour into simple sugars, which it then turns into carbon dioxide , water and alcohol. Dried active yeast is yeast that has been freeze-dried, formed into tiny balls and coated in a protective sealant. Well-known brands include Tandaco and Lion. Keep them in the freezer, where the little single yeast cells will slumber silently until you reawaken them by "dissolving" them in water. The water should be tepid. Not cold, not warm: think Hobart in late spring. Any warmer and the yeast will get a little bit overexcited and work too quickly. Don't add yeast and salt to the mixture together as salt can kill living cells through osmosis. It sucks the water, therefore the life, out of cells. Once you have made the dough, send it on a holiday to the north coast of NSW. Not too hot, not too cold: 25 degrees is perfect. This could be on top of the fridge where the heat rises from the motor, near the dryer in the laundry orin a warm sunny room, free from cooling drafts. If you have done all this and the yeast is still not working, chuck it out and buy another pack.

Letters: Green Tomatoes, Part 2

Since we founded the Brain Food Institute here at Good Food nearly a decade ago, we have collected a phalanx of loyal followers. One is 90-year-old D. Evans. She wrote in with an addendum to the ideas on how to prepare green tomatoes. She wrote, "I make green tomato chutney from this recipe every year. It's deliciously simple and old-fashioned. It comes from the Leader recipe book, which belonged to my mother-in-law. Wishing you and your family well through this singular time." Thank you, D. Evans. Here is the recipe. Take 1.8kg chopped green tomatoes, 1kg sliced onions, sprinkle with several tablespoons salt in a large non-reactive saucepan. Place over high heat and cook for 5 minutes until the vegetables begin to soften. Cool, cover, leave overnight. Next day, strain off the liquid, return to the saucepan, add 600ml vinegar and 1kg sugar, and simmer for 45 minutes. Add two tablespoons Keen's Curry Powder and one tablespoon of turmeric. Stir. Mix 150g flour with 150ml water to make a smooth paste. Stir through the simmering chutney and cook, gently stirring, until thickened. Place into sterilised jars with fitting lids while still very hot. Seal. Cool. Slather over cheese in a sandwich or serve with cold chicken salad. A most useful use of green tomatoes that stores well and makes quite a welcome gift.

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

• Correction: An earlier version of the green tomato relish recipe omitted 1kg sugar, which should have been added with the vinegar. The error was due to the author, Richard Cornish, who is in the sin bin for a week.