Al-jawab billahi at-taufeeq (the answer with Allah's guidance)
It is superior to use the right hand for all noble matters, for this was the way of the Messenger of Allah (Sallallahu Alaihi Wasallam).
It is narrated by Sayyida A'isha (RA) that the Messenger of Allah (Sallallahu Alaihi Wasallam) loved to start from the right hand side in purification as he purified himself, and comb his hair as he combed, and wear shoes as he wore shoes (from the right hand side)," (Ibn Majah)
In matters requiring dexterity, such as writing, there is no harm in a left-hander using their left hand. However, one should avoid eating with the left hand, because the Shaitan eats with his left hand. Also, to use the right hand is a specific Sunnah, and dignified conduct, to do so with the right hand.
Unless there is some hardship in using the right hand, such as it being broken, or another similar excuse that causes difficulty in using it to eat with. As for using the left hand only to add food to a morsel, as is the habit with many people, that is not an excuse, and Allah knows best.
