Porcini-Rubbed Beef Tenderloin with Roasted Portobello Mushrooms | Ideastream Public Media

Ingredients

• ¼ ounce dried porcini mushrooms or dried shiitake mushroom caps (about 8 small caps), broken into pieces
• 2 tablespoons fresh rosemary
• Kosher salt and ground black pepper
• 1 tablespoon black peppercorns
• 4- to 5-pound beef tenderloin roast, trimmed of fat and silver skin
• 6 tablespoons extra-virgin olive oil, divided
• 1½ pounds portobello mushroom caps, gills scraped off with a spoon, halved and sliced ¼ inch thick
• 1 medium sweet onion or yellow onion, halved and sliced ¼ inch thick
• 1 tablespoon sherry vinegar
• 1 cup lightly packed fresh flat-leaf parsley, roughly chopped
• Flaky salt, to serve (optional)