How to Make It
Make the salsa verde Mix the parsley, chives, tarragon, anchovy, garlic, and shallots together in a small bowl. Cover with the olive oil. Set aside until ready to use.
Place the eggs in a small pot, cover with cold water, and bring to a simmer. Remove from heat and let sit exactly 4 minutes. Remove the eggs from the water and transfer to an ice bath to stop the cooking. Once cooled, peel them and add only the yolks to the bowl of herbs along with the mustard. Mix together until blended—the consistency will be slightly textured, not smooth.
Once you’re ready to cook and serve the fish, transfer 3⁄4 cup of the herb base to a small bowl and whisk in the vinegar. Taste and add more vinegar if necessary— the sauce should have a bright acidic bite to it.
Rip the bread, spread the butter, dip in the salsa verde, add an anchovy, eat, and repeat!