Ingredients 1/2 cup extra-virgin olive oil, divided1 pound assorted cultivated and/or wild mushrooms (cremini, shiitake, oyster, chanterelle, porcini, etc.), trimmed of woody stems and thinly sliced1 tablespoon unsalted butterKosher salt and freshly ground black pepper2 medium shallots, thinly sliced (about 1/2 cup)4 cups baby arugula 2 tablespoons fresh lemon juice2 teaspoons Dijon mustard2 teaspoons honey3…