I bought a bottle of Modena balsamic vinegar (label says aged 4 years) about two months ago and have used a scant amount. The remaining contents have congealed in the bottle. Should I throw it away or is there a way to liquify it or otherwise make it useable?
I would throw it away. The best rule of thumb is when in doubt, toss it out.
Thanks for writing,
Timothy S. Harlan, M.D.