When I saw this in the September, 2009 issue of Bon Appetit I had to make it ASAP. My oh my is it ever good! We grilled the mahi instead of searing it. It really doesn't make a difference in the final product. I think this would be great with tilapia, halibut, scallops and even shrimp.
I'm definitely keeping the sauce recipe handy for more dishes. I bought white balsamic at Trader Joes because it was cheap but you could definitely substitute white wine vinegar.