Assalamu aleykum Ustadh, recently I´ve noticed with few people that, when they eat or drink, that they say Bismillah to begin and say Alhamdulillah after every bite/sip. Is this Mustahab to do over saying Alhamdulillah once after finishing the drink/food ? Is it correct that Sheikh Bin Baz did so ?

Ustadh AbdulAziz al-Haqqan
You say Alhamdulillah after you finish, not after every sip and every bite.