"Best" is not a word criticism should indulge lightly, but there are times when nothing else will do. In particular, the United production of Richard Strauss' "Salome," which public TV will broadcast tonight, is the most extrarodinary instance of televised opera I've ever encountered.

For once, the arts of musical drama and television imagery are fused with enough brilliance to deliver all that the combination of media seems to promise. More than that, this "Salome" manages to extend our notions of what is possible in the way of TV opera.

And to top even this, the performance - featuring soprano Teresa Stratas in title role, with Karl Bohm conducting the Vienna Philharmonic - succeeds in removing the blight of unsavory sensationalism which as often bedeviled this opus, without in any way compromising its lurid power.

Salome, you will remember, was the biblical teen-age minx who demanded - and received - the head of a saint on a silver platter as payment for doing an erotic dance with veils for her lecherous stepfather. A perennial problem in staging is finding a soparno who can look, sing, act and presumable dance the role with reasonable credibility in all these departments.

Stratas may not be the first to fill the bill, but it would be hard to imagine anyone closer to ideal. From a purely vocal standpoint, the most outstanding Salome of past memory was Ljuba Welitsch, who, at the time (the mid 50s) produced a thrillingly golden hued timbre that was unique in operatic annals. The Stratas voice is not quite on this plane, exquisite though it is.

But Stratas is also a superb musical artist and a formidable actress to boot. Many of her scenes in this production would be no less hair-rising with the sound turned off. With it on, what one gets is precisely that combination of amoral innocence and pathological intensity the role craves but so rarely receives. As a totality, her performance is nothing short of electrifying.

Commanding as she is, Stratas is not alone in her excellence. Bernd Weikl uses his stalwart baritone to project a Jochanaan of majestically somber authority. Astrid Varnay, though no longer in vocal prime, is a fearsomely apt Herodias, and the other principals are not less well cast. Conductor Bohm shades and paces the wondrously oaken sound of the orchestra with the utmost sensitivity to the expressive tides of the score. And someone had the good sense to call in Robert Cohan, for a long time a principal of the Martha Graham company and now active in London, to choreograph the Dance of the Seven Veils t potent effect.

Perhaps the most unusual aspect of the production lies in the canny use of the TV medium, though close-ups, shooting angles, cuts and visual rhythms, to underline the seductive fascination with evil that is the heart of the opera - a high tribute to the expertise of director goetz Friedrich.

if you see only one opera on TV, make this the one. Catch it locally on Channel 26 at 9 tonight, with a stereo simulcast on WETA-FM (90.0), or the repeat Saturday at 3 p.m.