I saw a video about preserving fresh tomatoes in wood ash. I started reading and it turns out, this can be done.

"Putting tomatoes in wood ash can extend their shelf life, according to several studies and traditional techniques. Farmers often face the challenge of preserving tomatoes during the season of abundance to ensure availability during periods of scarcity. Wood ash treatment has been found to be effective in reducing tomato rotting and extending shelf life. Specifically, treating tomatoes with 1.5 kg of wood ash per 1 kg of tomatoes was most effective in preserving them. This method is natural, chemical-free, and environmentally friendly, as it reuses ash from wood fires. However, it is crucial to use only untreated wood ash, as ash from treated wood or charcoal can contain harmful substances."