Cadfael, on ITV (UK)
IMDb; PBS (archived); TV Tropes; Wikipedia
streaming sites: Amazon; BritBox

This aired from 1994-98 in the U.K., and from 1995-99 in the U.S. This guy named Cadfael (Derek Jacobi) used to be a soldier in the Crusades or whatever. But later he became a botanist and monk who solved murders and stuff. I'm not sure how many installments I saw, but I do know I always enjoyed the show, and I'd really like to see it again someday, and write up a proper review.