SEATTLE _ If you have fear of cooking fish, well, so do I. It goes from just right to overcooked so fast! And a piece of overcooked fish is a sorrow, small but real. (I always think, morosely, "A fish died for this!") So more good news: Fish cooked in parchment paper is as dummy-proof as it gets. The two variations here _ one with potatoes, along the lines of Le Caviste, and one with asparagus, along the lines of thank-God-for-spring _ have cooking times that vary by five entire minutes. (Potatoes, even parboiled ones, take longer to cook than asparagus.) In the non-en-papillote world, cooking fish for five more minutes can be ruinous. Don't even worry about it! That fish is crimped snugly into its packet, all steamy-nice with butter and wine and lemon, plus herby-garlicky parsley sauce. The steaminess can't get out, so there's no danger of the fish drying out.
If you encounter trouble with folding and crimping closed the papers' edges, just use a paper clip at any questionable spots. (The pros at Le Caviste don't ever need to do this, but I've done it at home.) Then, you and your friend each get your own wrapped-up present of a supper. Serve with some baguette for sopping up the extra lemony-winey-buttery sauce, or just tilt your plate until it pools in one side of the packet and use a spoon. And when life gives you lemon slices this good, you should eat them.
