Question: When was sesame oil and tofu first used by vendors?
About the article "Pho", section "Development".

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Fermented tofu also called fermented bean curd, sufu, tofu cheese, or preserved tofu is a form of processed, preserved tofu used in East Asian cuisine as a condiment made from soybeans.
The ingredients typically are soybeans, salt, rice wine and sesame oil or vinegar, and are sold in jars containing blocks 2- to 4-cm square by 1 to 2 cm thick soaked in brine with select flavorings. 
Sesame was cultivated during the Indus valley civilization and was the main oil crop.
It was probably exported to Mesopotamia around 2500 BC and was known in Akkadian and Sumerian as 'ellu' (in Tamil also Sesame is called "ellu").
Sesame seeds were one of the first crops processed for oil as well as one of the earliest condiments.
In fact, the common word for vegetable oil in many Dravidian languages like Tamil, Malayalam and Kannada literally means sesame oil (in Tamil, எள் - sesame + நெய் - ghee/fat -> எண்ணெய்) .
The Hindi word for oil (Tel (तेल)) is also derived from sesame oil (from Sanskrit Taila (तैल), which means obtained from Tila (तिल) Sesame).
The Telugu word for sesame seeds isPrior to 600 BC, the Assyrians used sesame oil as a food, salve, and medication, primarily by the rich, as the difficulty of obtaining it made it expensive.
Hindus used it in votive lamps and considered the oil sacred. 
A rather famous hot Sichuan preparation using firm Asian tofu is "mápó dòufu" ().
This involves braised tofu in a beef, chili, and a fermented bean paste sauce.
In the Shanghai region it is called "málà dòufu" ().
Dried tofu is usually not eaten raw but first stewed in a mixture of soy sauce and spices.
Some types of dried tofu are preseasoned with special blends of spices, so that the tofu may either be called "five spice tofu" ( wǔxiāng dòufu) or "soy sauce stewed tofu" ( lǔshuǐ dòufu).
Dried tofu is typically served thinly sliced with chopped green onions or with slices of meat for added flavor.
Most dried tofu is sold after it has been fried or pre-stewed by tofu vendors.
Soft tofu can also be broken up or mashed and mixed with raw ingredients prior to being cooked.
For example, Japanese "ganmodoki" is a mixture of chopped vegetables and mashed tofu.
The mixture is bound together with starch and deep fried.
Chinese families sometimes make a steamed meatloaf or meatball dish from equal parts of coarsely mashed tofu and ground pork.
In India, tofu is also used as a low fat replacement for paneer providing the same texture with similar taste.
Tofu bamboos are often used in lamb stew or in a dessert soup.
Tofu skins are often used as wrappers in dim sum.
Freeze-dried tofu and frozen tofu are rehydrated and enjoyed in savory soups.
These products are often taken along on camping trips since a small bag of these dried tofu can provide protein for many days.
Japanese 'miso soup', stocks with miso paste, is frequently made with tofu.
In Korean cuisine, soft tofu, called "sundubu" (순두부), is used to make a thick stew called "sundubu jjigae" ().
Firm, diced tofu often features in the staple stews "doenjang jjigae" () and "kimchi jjigae" (). 
In Asia.
Tofu originated in ancient China, although little else is known about the exact historic origins of tofu and of its method of production.
The theory that tofu was invented by Lord Liu An of Huai-nan in about 164 BCE (early Han dynasty) has steadily lost favor among most scholars in China and abroad since the 1970s.
The claim concerning Liu An was first made by Zhu Xi during the Song dynasty (960-1127 CE) - roughly 1,000 years after the supposed invention.
The theory that tofu-making is shown in a mural incised on a stone slab in Han Tomb No.
1, at Da-hu-ting, Mixian, Henan province attracted much attention after about 1990.
Yet it too has lost favor because (1) no step of cooking the soy puree is shown in the mural, and (2) when Chinese food historians tried to make tofu without cooking the puree, the result was a tiny amount of unpalatable material.
Thus, while there are many theories regarding tofu's origins, historical information is scarce enough as to relegate the status of most theories to either speculation or legend.
Like the origins of cheese and butter, the exact origin of tofu production may never be known or proven.
The historical era starts in the year 965 CE (early Song dynasty) with the "Qing Yilu" by Tao Ku.
What is known is that tofu production is an ancient technique.
Tofu was widely consumed in ancient China, and techniques for its production and preparation were eventually spread to many other parts of Asia.
One popular dish, known as "Mapo Tofu", is a traditional food in China.
Its development likely preceded Liu An, as tofu is known to have been a commonly produced and consumed food item in China by the 2nd century BC.
Although the varieties of tofu produced in ancient times may not have been identical to those of today, descriptions from writings and poetry of the Song and Yuan Dynasty show that the production technique for tofu had already been standardized by then, to the extent that they would be similar to tofu of contemporary times.
In China, tofu is traditionally used as a food offering when visiting the graves of deceased relatives.
It is claimed that the spirits (or ghosts) have long lost their chins and jaws, and that only tofu is soft enough for them to eat.
Before refrigeration was available in China, tofu was often only sold during the winter time, due to the tofu not spoiling in the colder weather.
During the warmer months, any leftover tofu would be spoiled if left for more than a day.
Chinese war hero Guan Yu used to be a tofu maker before he enlisted in the army.
Chinese martial arts expert and hero, Yim Wing-chun, was a celebrated tofu maker in her village.
(Tofu as such plays a part in the 1994 movie about her life, "Wing Chun".
)Tofu and its production technique were subsequently introduced into Korea and then Japan in the Nara period (late 8th century) as well as other parts of East Asia.
The earliest document of tofu in Japan shows that the dish was served as an offering at the Kasuga Shrine in Nara in 1183.
The book "Tofu Hyakuchin" ( Dòufu Bǎizhēn), published in the Edo period, lists 100 recipes for cooking tofu.
The rise in acceptance of tofu likely coincided with that of Buddhism as it is an important source of proteins in the religion's vegetarian diet.
Since then, tofu has become a staple in many countries, including Vietnam, Thailand, and Korea, with subtle regional variations in production methods, texture, flavor, and usage.
In Southeast Asia, tofu was introduced to the region by Chinese immigrants from sea-faring Fujian province, evident from the fact that many countries in Southeast Asia refer to tofu by the Min Nan Chinese pronunciations for either soft and firm tofu, or "tāu-hū" and "tāu-goan" respectively.
In Indonesia, Malaysia, Singapore, Thailand and the Philippines, tofu is widely available and used in many local dishes.
Tofu is called "tahu" in Indonesia, Indonesian dishes such as, tahu sumbat, taoge tahu, asinan, siomay and some curries, are often add slices of tofu as ingredients.
In addition, tahu goreng, tahu isi and tahu sumedang are the popular fried tofu snacks.
Tofu is called "tauhu" in Malaysia and Singapore.
The Malaysian and Singaporean Indians use tofu in their cuisine such as Indian mee goreng, rojak pasembor.
The strait peranakan cuisine often uses tofu, such as mee kari Penang, and laksa.
The makers of tofu in these countries were originally the Chinese but tofu now is made by non-Chinese as well.
Tofu in the Philippines is essential to the daily diet, as "taho", widely eaten as breakfast, or "tokwa" (a dry fried variation), which is a staple or alternative to meat in main meals, and in numerous regional dishes.
Tofu was introduced to the archipelago in the 10th to 13th centuries by Song Chinese mariners and merchants, along with many different foods which had become staples of the Philippine diet.
The use and production of Tofu were first limited to urban centers with influential Chinese minorities, such as Cebu or Tondo, but were quickly spread to even remote native villages and islands, long before the Spanish arrival in the 17th century. 
Onsen water is used to make this delightful local dish.
The alkaline in the water makes the bean curd in the "tofu" soft and mellow when it is heated in ceramic pots.
"Onsen tofu" is traditionally served with condiments such as green onion, ginger, and sesame paste to taste.