I have fond memories of performing this piece with Alessandro Siciliani (It doesn't get any more Italian than that!) and the Columbus Symphony in 1995. The audience seemed to like it, too.
This recording was on cassette tape, so the sound wobbles a bit at times.
I had fun writing my own cadenza, in which I quote from the end of Weber Clarinet Concerto No. 2. The sextuplet riffs seemed to fit with this showoff piece. It was not uncommon to quote contemporary composers music in cadenzas. Weber wrote his Op. 74 in 1811, and I believe the Rossini was written in 1812. (There is a different piece for clarinet by Rossini called Variations which was written in 1809. I welcome clarifications from readers if they can comment on this history)
To prepare for this musically, I listened to Maria Callas and other opera singers. One recording which deeply influenced me was a late live recital, 6/29.1969 by Elizabeth Schwarzkopf with Aldo Ciccolini. Though her voice was aging, the depth of music making was evident. She took musical chances I do not hear in her earlier recordings. No Rossini on the program: Schubert, Schumann, Wolf, Mozart, and more romantic composers.
The theme and variations are in Bb, but the introduction is in Eb. I've seen programs that list is either way.
Giacomo Rossini, Introduction, Theme and Variations