Any particular reason, or just left-handed?
If there's a real need, you might just take a normal right-handed one, flip it over, and run it with the pod on top of the bar on the left side. Ergonomics won't be perfect, but I think if you rotate it a bit, you might be OK.
I flipped my bike around to take a look at how it would feel, and Shimano's Deore dual-control levers (which I have) didn't feel too bad. Downshift via the thumb lever is OK, if not ergonomically perfect. Upshift to smaller cog is accessible via the index finger trigger only, as the bar blocks thumb access. But if you're OK with that, you might give it a try.
Probably your best shot. I'd only try it if I was running a 1x9 and there was a situation where I had limited use of my right hand for some reason.