A fatty cut of beef is best for this red curry as it will prevent the meat from drying out when cooking. Serve with raw vegetables such as cucumber and bean sprouts.
In a saucepan, combine the beef, stock and salt to taste. Simmer until beef is cooked, about 20 minutes. Drain, reserving the stock.
In a frypan, heat the vegetable oil and fry the curry paste 5 minutes or until fragrant. Add the beef and fry 10 minutes, moistening with the stock as needed. Season with fish sauce and a little sugar.