Baking fish in a parchment packet is a classic method, and one modern cooks could use more freely for quick weeknight meals. First of all, you need not use parchment, foil works just fine (in fact, if you pack the fish fillets in foil you can throw them on the grill instead of heating up the oven - perfect for summer!). Second, the seasonings you add are endlessly flexible. Here I've used slivered ginger and green onions with a drizzle of toasted sesame oil. Try julienned summer vegetables like zucchini, tender carrots, and sweet onions, or use a mince of garlic and chile. Whatever seasonings you use, know that the fish will stay moist and tender without adding much (or any) oil.