15 Minute Shrimp Udon Noodle Soup

Name: 15 Minute Shrimp Udon Noodle Soup
Ingredients: 2 tablespoons sesame oil; 1 small onion (chopped); 32 oz beef broth (divided); 1/4 cup soy sauce (sliced green onions, peanuts for toppings); 2 tsp garlic powder; 1 tablespoon ginger powder; 2 teaspoon red pepper flakes; 1 teaspoon pepper; 1 teaspoon salt; 1 lb raw medium shrimp, peeled & deveined; 8 oz Udon noodles; 1 cup peanut butter (creamy is fine, if you prefer. Use all-natural peanut butter for the best flavor.); 1 cup sliced cabbage (sub mushrooms, thinly sliced carrots, spinach, or other favorite veggies)