An innovative but actually old-fashioned preserving technique that many chefs, including vegans, are using is dehydration. This is the concept behind powdered vegetable stock or dried soup stock, which is, fundamentally, portable soup, relied upon by sailors and explorers and campers. You will perhaps have used sun-dried tomatoes. Modern chefs scatter dried fruit powders over desserts, and ingredients like dried beetroot powder are fantastic for colouring pasta and tofu. Dehydration is also the theory behind fruit leather. You can buy a dehydrator, use the bottom oven of an Aga or a normal oven with just the light on or on its lowest setting of 60°C. You can also use the sun to dehydrate if you live in a hot country. When dehydrating fruit, choose mature but firm, undamaged fruits. To dehydrate vegetables, do not cook beforehand if it is something you could eat raw; if you would usually cook it, then steam the vegetable for 5–8 minutes before drying.