Kind of like guacamole but smoother and thinner; an awesome taco accompaniment.
Tomatillos, avocados, garlic-onion-cilantro-lime- you'll love it!
Here's a pic of it on some steak tacos:
Here's the recipe:http://www.cbfishes.com/2012/08/26/cb-cooks-avocado-tomatillo-salsa/
I haven't tried it on fish, but I bet it would be simply amazing on some fish tacos.