I'd like to make this with fish that's not whole (salmon steaks, about 1.3 pounds). What should the cooking time be? I'll be adapting the flavors...

I would bake it for 20 minutes at 350 or at 425 for 10 minutes depending on the thickness of the salmon steaks.

I make salmon in foil packets and have experimented with both temperature timing. I live in a region where frozen filets are a better option than fresh amd I would say the pieces I get are four ounces or under. I set the oven fairly high, perhaps around 400 and wrap the salmon in parchment paper along with lots of sliced onions, garlic, lemon and herbs. After about 20 minutes, I open the oven, set the baking dish on top of the stove and put my ear close to the packet. If I hear a bit of sizzling, it is ready to eat. If the packet is not speaking to me, it goes back in the oven umtil it has something to say!

I hate to tell people its done when its done. But, when it comes to fish..I do have a rule of thumb that has helped out from the Canadian Fisheries. 10 mins for every 1" of thickness. Its not precise but it gives you a measure. Hope this helps.

Come now, AntoniaJames, use your kitchen confidence! Bake them at the same temperature until the salmon is cooked through.