Surprisingly, it was quite simple to copy, and it can be altered to suit taste and budget. It is found in the Pacific, from California to Chile. The fish has pretty white flesh and a mild sweet flavor. But don't let that dissuade you from trying the recipe. Striped bass or grouper or even ordinary mild fish fillets from the supermarket can be substituted.
Hazelnuts also tend to be pricey and scarce, but they, too, can be substituted.
I've used walnuts with great success. As for the sauce, don't let the French name scare you. While it requires constant attention during preparation, this rich sauce is not difficult. At the brunch, the fish was served with lemon vermicelli noodles and vegetables. I used lemon pepper pasta and fresh asparagus.