Pla Tuu is a type of fermented fish popular in Isan and Northern Thailand. Pla thuu differs from the more widely eaten pla ra because it has undergone fermentation for two or three months. The result is a rather pungent fish, often eaten with chili sauce and vegetables such as green mangoes. Pla thuu is often made from mackerel (pla khem or pla kem) but can also be made with tuna.
Northerners call fermented fish by the name 'pla ra' and it is often eaten with raw vegetables such as green papaya and ginger, and with chili sauce. The sauce is made from dried red chilies soaked in vinegar with garlic and sugar added. The dish has a strong smell but good taste.
Pla ra that is fermented for a month or two and then eaten immediately. Pla ra plao which means quick-fermented fish. It is also known as ' pla bpet ', fermented in a bamboo tube with only salt added to speed up the fermentation process. The sauce is made from small fresh chilies, garlic, fish sauce and sometimes tomatoes. It is easily made at home but the fish will only be ready for eating after two or three months. When it is just about to be eaten, it is fried with chopped garlic and vegetables such as green mangoes, cabbage and beansprouts.
Pla ra is fermented in a jar or a tin can. The fish is often salted at the beginning but this step may be skipped if it is to be preserved for a short time. It will, however, increase the fermentation time and produce a stronger taste. After about a week, the liquid from the fish will form a white layer on top. This means that fermentation has taken place and it is ready to eat or can be preserved and eaten later.
Sour fermented fish ( pla ra ). Fish that has been salted and left for a few days, then mixed with chopped onions and other seasonings such as black pepper, coriander seeds and grated garlic. It is kept in a jar submerged in water so that the fish remains under the water to ferment.
Pla ra is used as a seasoning for som tam (spicy green papaya salad), larb, and other Thai salads. It is also an important seasoning for kanom chin nam ngiao , a sour noodle dish from Buriram Province in Northeastern Thailand, and it is often added to kanom jin nam ya , a Burmese-influenced curry from the same region.
Sour fish is also one of the ingredients in Yum pla dook foo, a salad from Ubon Ratchathani Province that includes string beans and raw egg yolks. It is also eaten with raw vegetables, such as green papaya and ginger, or with chili sauce. Pla ra is also an ingredient of nam phrik pla, a popular condiment of central Thailand.