When her lover is arrested for treason, after aiding an escaped political prisoner (bass Scott Conner in a small but pivotal role), Tosca is offered an unholy bargain by the corrupt and lascivious police chief Baron Scarpia: either she offers herself up to his lust or the painter dies. He is the painter and revolutionary Mario Cavaradossi and she a famous singer, with the temperament to go with it: jealous, melodramatic and passionate.

Matching her note for note is the handsome tenor Brian Jagde, a Merola alumnus and former Adler Fellow who strikes some sparks with his lady love, both vocally and dramatically. Blessed with a voice that is as beautiful as the rest of her, Haroutounian is a fine actress as well and, if she is not destined for a big career, I’ll eat my computer. The frosting on the cake is a stupendous San Francisco debut by Armenian soprano Lianna Haroutounian in the title role.

What comes out of the oven is San Francisco Opera’s “Tosca,” pretty digestible but not a wholly satisfying gourmet dish. Take one good-looking couple, she a fantastic soprano and he a very good tenor, add a not-very-threatening villain, a heavy-handed conductor, mix well and bake for a little over two hours.

Tosca opera youtube s f