The grand-mufti of Pakistan, Hadhrat Mufti Mohammad Shafi’ a senior khalifa of Hakim al-Umma Hadhrat Mawlana Ashraf ‘Ali Thanawi (may Allah have mercy on them) said, “There are numerous minor (sagerah) sins.
All actions performed against the Sunna method are minor (sagerah) sins.
For example, one drinks water without reciting ‘bismillah’, this is a minor sin. Also, if one eats or drinks using the left hand, this is a minor sin.”
(Majalis Mufti-e-azam Albalagh J1,1410 pg 294)
Jazak Allah, very important lesson to learn indeed. May Allah give us the ability to act upon the sunnah of his beloved nabi (peace and blessings be upon him), ameen.