Srimad Bhagavatam Canto 10, Chapter 22, Text 01

  SB 10.22.1

sri-suka uvaca
hemante prathame masi
 nanda-vraja-kumarikah
cerur havisyam bhuñjanah
 katyayany-arcana-vratam
 
Translation: 
 
Sukadeva Gosvami said: During the first month of the winter season, the young unmarried girls of Gokula observed the vow of worshiping goddess Katyayani. For the entire month they ate only unspiced khichri.
 
Purport: 
 
The word hemante refers to the month of Margasirsa — from approximately the middle of November to the middle of December, according to the Western calendar. In Chapter Twenty-two of Krsna, the Supreme Personality of Godhead, Srila Prabhupada comments that the gopis “first ate havisyanna, a kind of food prepared by boiling together mung dal and rice without any spices or turmeric. According to Vedic injunction, this kind of food is recommended to purify the body before one enacts a ritualistic ceremony.”
Srimad Bhagavatam Canto 10, Chapter 22, Text 04