I start with a large piece of parchment folded in half, oiled on the inside surface. This time I layered chunks of lemon, grass-fed butter, toasted fennel seeds and coriander seeds, sliced onions, fennel and red pepper. Then I closed the parchment with tiny sharp folds all around the open edge. 15 minutes at the 425 temp my husband was using for his baked potato worked out just fine. You don't have to use such a high heat, just compensate by cooking a little longer. If you are worried about burning the fish, you can remove it from the oven and let it sit a little while since it will continue to steam. This was a luxurious, delicious meal which I rounded out with sauteed mushrooms and Italian parsley plus a gorgeous salad of baby kale, purple cabbage, carrots and radishes. I had so much food it took me half an hour to finish it all, then I felt I'd fed my cells instead of my belly.
Note: I receive no compensation from mentioning Vital Choice. I have just found it to be an amazing company which provides sustainably sourced, wild-caught seafood. The customer service is top-notch. Vital Choice was recommended by my doctors. Give it a google if you are so inclined.