Boil the beef tendon in water until tender. Skim off any foam to keep the broth clear. Once the tendon is soft, remove and cut into bite-sized pieces. Marinate with finely chopped lemongrass, garlic, seasoning powder, pepper, and fish sauce for about 20 minutes.

Heat oil in a pot over medium heat. Add lemongrass (cut into pieces and lightly smashed) and sauté until golden. Add a little chili oil for color and a bit of fish sauce for aroma. Add the marinated beef tendon to the pot, stir well, and cook on low heat so the meat absorbs the flavors. Once the tendon is well-seasoned, add the reserved beef tendon broth and bring to a boil. Toast the sesame seeds, crush them, and add at the end. Adjust seasoning to taste.

Soak the fresh herbs in salted water, rinse well, and mix together.

To serve: Place the fresh herbs in a bowl, add Quang-style noodles, ladle the beef tendon and broth over, then top with green onions, cilantro, peanuts, grilled rice crackers, lime, and green chili peppers.