Tirunelveli halwa is popular throughout India. It is a red or brown coloured, stickey, transparent, ghee floating sweet. The word delicious is not at all enough to describe the the taste of this Tirunelveli halwa.
You are right nowadays Iruttukadai halwa is popular in Tirunelveli. The meaning for Iruttukadai is a Dark Shop. Iruttukadai refers that there were no electric lights in the Halwa shop. People are saying that, even now the Halwa preparation and sales are done in the evening time with the help of candle-light.
It is nice to share Halwa with you. Tirunelveli is famous for Halwa for years unknown. The Halwa of Tirunelveli is not prepared by the people of Tirunelveli origin. For people of Tirunelveli " LALA KADAI HALWA" is very famous as the Halwa makers are LALAs who are Gujarati origin migrated and settled in Tirunelveli around the Temple car streets of Nellaiappar Temple. LALAs main trade is sweet stalls. Iruttukadai is the shop which still appears as it was originally constructed with wooden plank shutters. The shop doesn't have any tube lights. It has only one 40 watts bulb. They don't use even electronic balance to weigh. It is not strange that Tambiravaruni water is used to make Halwa. The whole Tirunelveli population depends on the water resource of the ever flowing Tambiravaruni river only. Every dish of Tirunelveli is prepared with the sweet Tambiravaruni water. Iruttukadai has become very famous in India by the lyrics of a song in Tamil film titled "SAMI". These days many make duplicate of this Halwas and sell in the name brand of IRUTTUKADAI. If one has tasted the original Iruttukadai Halwa he can easily detect the duplicate. Original is always Origial.
I know about Tirunelveli halwa which is very famous for the past 100 and more years. The LALA SWEET is a very famous sweet shop in all over Tamil nadu which is originated from tirunelveli. There are many shops are available in Tirunelveli for selling the famous sweet of halwa. The Halwa is a very sweet and good taste. The children likes halwa more. The preparation of halwa requires more gee and other things.
The IRUTTU KADAI HALWA is also famous in Tirunelveli. In early days, The halwa was sold out in night times using little lamp which does not make the shops more bright. The shops were seen as dark. So the name IRUTTU KADAI was given to the halwa shops.