Round rice noodles sit in a deeply simmered beef bone broth laced with lemongrass, shrimp paste, fish sauce, and chili for authentic central Vietnamese heat. Slices of beef and pork knuckle provide substantial protein, accompanied by rau ram leaves and banana blossom for contrast. The broth's mahogany hue comes from hours of reduction, delivering a spicy-sour punch that defines Hue-style soups. Diners often add chili oil to amp up the intensity.