In a large bowl, combine soy sauce, sesame oil, minced garlic, ground cumin, ground coriander, salt, and pepper. Add the thinly sliced beef, ensuring each piece is well-coated in the marinade. Cover the bowl with plastic wrap and let it marinate for at least 30 minutes at room temperature.

In a medium pot over medium heat, bring 4 cups of chicken stock to a gentle simmer. Whisk in 2 tablespoons of peanut butter until the mixture is smooth and creamy. Taste and adjust seasoning with salt or additional spices if desired.

Prepare the rice noodles according to the package instructions, usually requiring boiling them for about 3-5 minutes until just tender. Drain and rinse briefly under cold water. Set aside.

Heat a large skillet or wok over high heat. Add the marinated beef in a single layer and quickly stir-fry for 2-3 minutes until browned and cooked through.

Once the beef is seared, add the cooked rice noodles directly into the warm broth, followed by the beef. Stir to combine and adjust with fresh lime juice.

Ladle the soup into bowls while hot, garnishing with fresh bean sprouts, cilantro leaves, and diced red chili.