How to Make the Ultimate Umami-Bomb Vegetarian Demi-Glace
3/4 cup walnut halves (3 ounces)
1 large shallot, minced
2 tablespoons sherry vinegar
1 1/2 teaspoons Dijon mustard
1/4 cup plus 2 tablespoons extra-virgin olive oil
Salt and freshly ground pepper
3 endives, cored and cut crosswise 1 inch thick
1 medium radicchiocored, halved and thinly sliced
1 arugula bunch, thick stems trimmed
1/4 cup flat-leaf parsley leaves
3 ounces thinly sliced prosciutto, fat removed, prosciutto torn in to pieces
Preheat the oven to 350°. Spread the walnuts in a pie plate and toast for about 8 minutes, or until fragrant and golden. Let cool.
In a large bowl, combine the shallot with the vinegar and let stand for 5 minutes. Whisk in the mustard, then in a thin stream whisk in the oil. Season generously with salt and pepper. Add the endives, radicchio, arugula, parsley and walnuts and toss to coat. Top with the prosciutto and serve.