The Bengali plate from an eater's viewpoint:
At any given point of time, you can classify the Bengali plate, as per the consumer, to consist of one or more of the following kinds of food - "charba, choshya, lehya, peya". These four parameters are how food is consumed by the eater - 'charba' refers to the food items one can chew and consume, 'choshya' is to be sucked and eaten, 'lehya' are those things one may lick, and 'peya' indicates at the things one may drink. These four methods may often merge - a dish may involve one or more methods of consumption. In that, the 'chutney' mostly is classified in the third category - that is, to lick.
The Origin of Chutney
The term 'chutney' or 'chatni' as it is known in Bengal, indicates the method of consumption - coming from the Hindi word 'chat', 'to lick', that has connotations in the Sauraseni Prakrit term 'chat', indicating the action of eating something noisily and with a great deal of enjoyment. There are many varieties of chutney that can be traced back to as far as 500 BC, and the presence of the chutney in the Indian culinary lexicon is indisputably considerable. From the ones that are aged and matured for months and years to the quickly prepared ones, the presence of chutney is extremely important to the plate, and there are multiple reasons why the chutney is present in the meal. Of course, the most important is a quick refreshment of the tastebuds, a contrast to the existing flavours on the plate, like a sort of palate cleanser, to be honest. But chutneys serve other, more important purposes, like aiding in digestion, cooling down the body, reducing inflammation or tantalising the tastebuds when there's a lack of appetite.
Sweet and Sour Endings
Typically, in Bengal, a chutney is served at the end of a major meal for the day, like lunch or dinner, and is seen as a form of the digestive, that ends a meal on a sweet and sour note and is, therefore, a welcome end to a meal in the summer. As a child, I would often find chutney served in my household between March and October for lunch, and it would be at the end of a meal. Early summers would see the appearance of mangoes and bael in the household, to be made into thick, sugary murabba, which would be then aged in the sun for at least a couple of months before it would be deemed fit for consumption. However, they rarely lasted that long, thanks to marauding fingers of tiny mites such as I, and the happiness of stealing them straight from the jar and eating them with a great deal of relish and trepidation (for the fear of being found out) is a fond set of memories from my childhood. However, some chutneys would be prepared and consumed within a day or so, and amongst these were runny raw mango chutneys, pineapple chutney and a perennial favourite was the simple tomato chutney, which would veer between hot, sour and sweet, and a great way to end lunch on a hot summer afternoon.
The tomato didn't gain popularity in Bengal until quite late. In fact, up until the late 1800s, the tomato was seen as an exotic vegetable, and associated with something 'foreign', which resulted in the term 'biliti begun', which can be translated as 'foreign aubergine'. In the book 'Curry: A Tale of Cooks and Conquerors', Liz Collingham notes that tomatoes started to get quite popular in the 1880s. "The Bengali names of many European vegetables indicate that the Bengalis were introduced to them by the British. Tomatoes are referred to as biliti begun or English aubergine. It took longer for tomatoes to become popular, but George Watt noticed in 1880 that although they were still "chiefly cultivated for the European population... Bengalis and Burmans use [them] in their sour curries." Nineteenth-century tomatoes were sourer than the ones we are accustomed to today and they were particularly well suited to the Bengali style of sweet-and-sour cookery." (Collingham, p. 166) It can be said that in this spirit the tomato might have started making an entrance into the Bengali foodscape, and given the proclivity of imaginative cooks, they got inducted into different preparations slowly.
Ayurveda suggests that tomato is a rajasic ingredient, and increases vata, kapha and pitta dosha in the body due to its tendency of remaining sour even after digestion, resulting in acidity and flatulence, the addition of cumin and pepper can reduce these effects. This is probably the reason why the tomato chutney recipe made by my mother would have a bit of black pepper in it.
The most common method of preparing tomato chutney is with a touch of ginger and pepper in my household and dates back to the 1950s at the very least. This doesn't contain other popular additions, like dates and mango leather (aamshotto), but it does have a healthy bite from the addition of red chillies. It is advised to use ripe, red tomatoes for this particular recipe, and freshly cracked pepper, and the result is rather wonderful on a hot summer's afternoon, at the very end of a meal when a ladleful of the chutney would be unceremoniously dumped unto the plate after finishing off everything else. It is also important to note that as per my grandmother, after consuming chutney or anything sour, one should not drink water immediately, because it affects the throat and can induce congestion in the chest. So, the prudent thing to do would be to arrange for something sweet right after the chutney, so that one may finish the meal on a sweeter note.