Spicy Ramen with Beef and Bok Choy

Name: Spicy Ramen with Beef and Bok Choy
Ingredients: 1 pound lean ground beef; 1 tablespoon hoisin sauce; 1 tablespoon soy sauce; 2 tablespoons chopped scallions; 2 tablespoons chopped peeled ginger; 3 cloves garlic, chopped; Kosher salt and freshly ground pepper; 2 tablespoons vegetable oil; 1 1/2 cups sliced shiitake mushroom caps (about 6 ounces); 4 heads baby bok choy, quartered lengthwise; 4 3-ounce packages instant ramen noodles (preferably spicy-flavored), 1 flavor packet reserved; 1 Fresno chile pepper, seeded and thinly sliced lengthwise