• Pour a full pack of baking soda in the sink
• Pour double the quantity of vinegar
• Let it sit for 15 mins.
• Insert “The Drain Weasel hair clog tool” and clear the path for water to go down. Use the same to remove any clog (ex:- hair).
• Once all the vinegar goes down the drain, pour some boiling water into the sink.

See also:

• https://www.thespruce.com/freshen-and-unclog-drain-with-baking-soda-1900466 - more verbose and covers all the details; has pictures.