apply a sinkful of boiling water from your spaghetti pot and let stand.
repeat.

you will be buying a plastic probably 1-1/4" trap for this sink unless
it already has one. take its picture and it to the hardware store and
buy any other connected items that break when you remove it.

if not improved, remove metal trap, replace with plastic trap, it's
easier to remove the next time and less likely to rust thru too. often
can be removed by hand.

if no plastic obstructions are found at trap removal, snake out hair
and soap scum in pipe. inspect with flashlight and dental mirror.
reassemble. flush with hot water.

other tools: disposable vinyl gloves.