Mushrooms with Ginger, Soy, and Spring Alliums (v, gf)

I love to cook mushrooms en papillote because it’s extremely easy (you just assemble the ingredients on a sheet of parchment, fold it up and bake it) but there’s a little performance in the serving. These were the main course for my pop-up last month at Hudson Table, and we brought the parchment packets out to each guest along with a pair of scissors, s…