Salmon. Who doesn't like salmon?

 

You can broil it or sauté it or bake it. Add a bit of salt and pepper, maybe a little lemon juice. I like to coat it with panko (coarse bread crumbs) and sauté it in butter. But it doesn't really need any seasoning. And you can substitute any other fish.

 

I won't say too much about checking for the best kind of fish to buy, mercury-wise. It's all so depressing. I think it's best to buy fish from the US but I'm not totally sure of that. It may depend on the fish. I'd probably worry more if I were younger.