Smoking was another technique used for storing food. In the days when charcoal or wood-burning stoves were still in general use, a woven bamboo grate would be hung over the stove and dried fish or salted beef would be set on it to be flavoured by the smoke rising from the fire. It could be kept for a long time and would be safe from ants and other insects.
Once the food has been preserved in this way, how can it be used in preparing meals? Many recipes that call for dried ingredients are so perfectly suited to them that if they are made with fresh ingredients they are not nearly as good. One especially well known example is the clear, vegetable soup-like dish called kaeng lieng. The seasoning paste used to make it consists of shallots pounded with pepper and kapi. Salted, dried snakehead fish is then added (other kinds of crispy dried fish or finely-pounded dried shrimp can be substituted), then fresh vegetables. The result is a richly flavoured dish with a taste and aroma all its own. If fresh fish or shrimp is used, the dish is no longer kaeng lieng.
Another popular food with a dried main ingredient is nuea khem tom krathi hawm daeng (salted beef simmered in coconut cream with shallots). Thinly sliced dried beef is cooked slowly in coconut cream until extremely tender, then sliced shallots and palm sugar are added. The dish has a distinctively delicious flavour, and while it is still good if made with fresh beef, the salted beef version is better.
Some preserved ingredients are used as seasonings, such as tang chai, which consists of the stalks of various vegetables that have been salted and dried, then packed in bottles for sale. Tang chai goes into pork noodle together with crisp-fried garlic in oil. The tang chai acts as a flavour enhancer, and brings out the taste of the ingredients far better than the MSG generally used now. The noodle vendors of the past had deeper knowledge and superior kitchen skills than most of their counterparts today as well. These days the accent is on simplicity and speed, which means that many corners get cut. MSG is cheaper and easier, so that's what is used.
Nowadays the prices of fresh and dried foods and cooking ingredients like meat, eggs, seafood and all kinds of vegetables are very high. People who cook for themselves can't avoid buying these ingredients, and they are not sold in small quantities. Even fresh coriander and spring onions go for five baht a bunch, and the fiery chillies called prik khee nu cost 10 baht. You can no longer get them for less. When the prices of all of these essential ingredients are added up, it comes to a lot of money. If the dish can't all be eaten at once, even when the leftovers are put in the refrigerator it is only good for one more meal. If any is left after that, no one will want to eat it for a third time and it is usually thrown away.
So it is a good idea to take the old-fashioned principle of keeping leftovers and putting them to use, with certain variations, as ingredients for new dishes. One easy-to-prepare example is the northern Thai favourite called kaeng ho. After finishing a meal of kaeng khio wan (a spicy, coconut cream-based curry), gai pad khing (chicken stir-fried with ginger and wood ear mushrooms), stir-fried vegetables, kaeng som (a soup-like dish with a sour-sweet-mildly spicy taste), pad cha pla krai (a spicy aromatic fish stir-fry), or pla duk pad phet (a spicy catfish stir-fry), any leftovers can be put in the freezer.
When a number of different dishes have accumulated they can be taken out and allowed to thaw. Then some of the curry paste used to make the spicy curry called kaeng phet is fried in a wok to release its fragrance, and all of the thawed leftovers are added to the pan and fried together. Pickled bamboo shoots, aubergine, feathery cha-om shoots and glass noodles are put in, the dish is seasoned to taste, and crisp-fried shallots are sprinkled over the top. The result will be a nice, home-made kaeng ho assembled from leftovers.
Another example makes use of leftover grilled catfish. Grilled catfish are inexpensive; they cost about 20 baht each. But one, eaten with pounded dried chillies in nam pla, is not enough to make a satisfying meal, and more than that might be too much. Leftover catfish meat can be pounded in a mortar until it puffs up and then fried. When it gets crisp, take it from the fire and set it aside, then make a nam yam (a sour-hot sauce) from chopped unripe mango, sliced shallots, sliced prik khee nu, nam pla, sugar and lime juice. Toss it with the fried catfish meat, scatter some mint leaves on top, and the leftover grilled catfish is reborn as a first-class yam pla duk fu.
If a meal ends with some of the salted fish uneaten (in Thailand the fish might be pla kulao, pla seesiad, or pla sala), the meat can be removed and deep-fried. Then some ground pork can be fried with curry paste and the fried, salted fish meat added. Season with sugar and kaffir lime leaves and a new dish will result that combines saltiness, sweetness and spicy heat, and one that will make your mouth water.
One simple dish that Thais eat often is nam prik kapi (a spicy chilli dip sauce) with fried mackerel. If some of the nam phrik and the fish are left over, fry the sauce with rice, then remove the meat from the mackerel and add that, too, to make a fried rice dish that is ideal with a selection of fresh vegetables.
These are just a few examples of ways in which leftovers from dishes that we eat often here in Thailand can be given a new lease of life through creative cooking. Not only do these recipes help save money, they can also produce some dishes that might become family favourites in their own right.