The Thai noodle dish made with flat rice noodles and thick gravy is called rad na.
Rad na, also written rat na or lad na, is a Thai-Chinese noodle dish. It uses wide, flat rice noodles that are stir-fried before being covered with a savory, thickened sauce. Common toppings include chicken, pork, beef, seafood, or tofu, along with Chinese broccoli, known in Thailand as kai lan, and garlic.
The gravy is typically made from stock and fermented soybean paste, then thickened with tapioca starch or cornstarch. Soy sauce, fish sauce, and white pepper provide seasoning. At Thai restaurants, diners may add sugar, vinegar-soaked chilies, fish sauce, or dried chili flakes to balance the rich sauce.
The name is often translated as “topping,” describing the gravy poured over the noodles. Rad na is sometimes confused with pad see ew because both can use wide rice noodles, but pad see ew is primarily a dry stir-fry with dark soy sauce. Khao soi is another different dish: it is associated with northern Thai cuisine and features curry broth and noodles rather than rad na’s poured gravy.