1Bring a large pot of salted water to a boil. Add the asparagus and blanch for 2 minutes. Using a spider, remove the asparagus from the boiling water to a colander set over the sink. Add the shelled fava beans to the boiling water and blanch for 2 minutes. Using a slotted spoon or a spider, remove the fava beans and add to the colander with the asparagus.
2Fill a small saucepan with about 2 inches of water and set over low heat. Cover with a heat-resistant glass bowl (big enough to hold 2-3 cups of liquid).
3In a medium saucepan set over medium-high heat, combine the shallot, vinegar, and wine. Cook 5-8 minutes or until reduced to about 2 tablespoons.
4Turn off the heat source and allow the shallot mixture to cool slightly, about 2-3 minutes. Over low heat, add the butter three pieces at a time, whisking until almost completely emulsified. Continue until all of the butter has been combined. Stir in the thyme and season with a pinch of sea salt and fresh ground pepper. Taste and adjust seasonings.
Add the sauce to your prepared glass bowl set over the simmering water (this will keep your sauce warm without separating).
5In a large cast-iron skillet set over medium-high heat add 1 tablespoon of extra virgin olive oil to coat. Add the halibut filets and cook for 3 minutes. Gently flip the halibut filets over and cook for 3 minutes. Add the blanched asparagus and fava beans to the skillet, stirring them frequently. Remove the skillet from the heat.
6Plate the halibut filets, asparagus, and fava beans. Pour the sauce over the filets and serve immediately.
Grilling in aluminum foil packages is a practical riff on the French technique en papillote, where ingredients are wrapped in parchment paper and baked. The food steams, making it tender and flavorful.