It seems that steaming fish in paper is a relatively popular (not to mention healthy!) method of preparation, yet it's something I had never done myself. I've roasted potatoes in foil, so how different could it be? Well parchment paper is not tin foil, it doesn't grab and stick to itself in the same way. So although the principle is the same, there is a certain folding technique that guarantees a secure little packed when using paper.
There are several ways out there of securing your paper parcel, Le Cordon Bleu at Home suggests brushing the edges of the packet with an egg white wash and folding them over, using the egg wash as a kind of adhesive. In The Herbfarm Cookbook, however, Jerry Traunfeld describes a technique where the paper is cut into the shape of a heart and overlapping creases are made around the edge of the paper to secure it. I liked the idea of folding in this manner and thereby saving myself an egg. While the recipe I used does comes from The Herbfarm Cookbook, Charlie Trotter's chapter on Vegetables in Jill Norman's The Cook's Book shows in pictures what Traunfeld describes. Pictures being infinitely easier to follow, I used Trotter's technique, and thought you might benefit from a few images as well.
Fish Fillets en Papillote with Grapefruit and Tarragon
About 1.5 lbs of medium-firm fish fillets, in this case, cod.
2 tablespoons unsalted butter
A few green onions (I replaced one shallot with these), thinly sliced
Zest of 1/4 grapefruit
Segments from 1 large grapefruit
1/4 cup very coarsely chopped fresh French tarragon leaves
Oven preheated to 425
To start, cut as many nice big pieces of parchment paper off your roll as number of fish fillets you're preparing. Traunfeld suggests that each be somewhere near the 24 x 16" mark. Fold each sheet in half and, in a throwback to your kindergarten days, cut out a half-heart shape as large as your paper, as though you were making a valentine. Unfold your hearts and lay them out flat.
Put all of the ingredients in the center of one side of the heart and fold the remaining side over.
Starting at the top of your half heart, begin crimping the edges down, making sure they overlap, by folding one piece of the edge over and creasing firmly. Moving along the outside of the heart, continue folding and overlapping, making sure that your folds overlap by about half.
Once you reach the bottom of your heart, twist the point and fold it under so that all of your crimping will stay in place.
Move your packets onto a baking sheet and bake for 10-12 minutes. The paper should puff and brown. Remove the packets from the oven, cut them open and you're all set to go!