How to Make It
Heat 1 teaspoon oil in a Dutch oven over medium-high. Add half of beef; cook, turning occasionally, until browned on all sides, about 6 minutes. Transfer cooked beef to a plate. Repeat procedure with 1 teaspoon oil and remaining beef.
Heat remaining 4 teaspoons oil in Dutch oven over medium-high. Add onion, garlic, and ginger; cook, stirring often, until onion is almost tender, about 6 minutes. Stir in tomatoes, sambal oelek, miso, coriander, and pepper; cook, stirring constantly, 1 minute. Add stock, soy sauce, brown sugar, and browned beef. Bring to a boil; partially cover, and reduce heat to medium-low to maintain a simmer. Cook until beef is almost tender, about 45 minutes. Add mushrooms; cover and cook until beef is tender, about 30 minutes.
Cook noodles according to package directions; drain and rinse with cold water. Drain well.
Add bok choy to soup; cover and cook until crisp-tender, about 4 minutes. Arrange about 1/2 cup noodles and 2 bok choy quarters in each of 8 bowls. Ladle about 1 1/2 cups soup into each bowl; sprinkle each serving with 1 tablespoon green onions. Top with cilantro sprigs.