The tenth day of Onam is known as Thiru-Onam which literally also means second Onam. In 2016, Thiruvonam date is September 13.
According to the religious history, it is largely believed that it was on this day Vamana suppressed Mahabali to underground. At this situation, Mahabali requested Vamana that he wishes to return in order to meet his people and wholeheartedly bless them. The day marks return of Mahabali according to his received boon to visit his fabled land that is Kerala.
On the other hand, this particular day is highly considered very auspicious because the day marks the birthday of many temple deities such as Sree Padmanabha Swamy of Thiruvananthapuram and Vamana of Thrikkara temple etc.
Onam is purely a traditional Hindu festival which is celebrated with lot of fun and joy. In the modern age, this festival has really emerged as one of the secular festival. Moreover this festival is largely associated with the yearly harvest time of the state of Kerala. All the family members have early bath and wear the new dress. They also distribute wholeheartedly alms to the poor and needy too..
Triuvonam’s most important activity is the grand Thiruona-Sadya. It is considered as the most sumptuous feasts prepared ever by any mankind in this world. The special feast is served on large plantain leaves. The feast consists of nearly 13 to 15 curries along with regular food items. There is a saying in this region that “Kanam Vittum Onam Unnanam” which literally means “We should have the Thiruvonam lunch even if we have to sell all our properties”. This statement really indicates the importance of Onam-Sadya on the day of Thiruvonam.