Wretman is perhaps best known for introducing cooking to men in Sweden, and his work as a restaurateur founding several of Stockholm's most popular restaurants.

[2] Wretman did not succeed in school, and at the age of sixteen he began apprenticing in the kitchen at the Hotel Continental in Stockholm.

[5] At Maxim's he learned the basics in the kitchen and was an apprentice under chef Louis Barth and restaurant owner Albert Baser.

[6][5] In 1937, Wretman worked as head of the bar at the restaurant Soleil de Minuit in the Swedish pavilion at the Exposition Internationale des Arts et Techniques dans la Vie Moderne.

[7] There he became acquainted with Sara Reuterskiöld, who was about to open the restaurant Regnbågen; she hired Wretman as head chef.

In 1941, he started working on the Finnish cargo ship SS Winha, so he could return to Sweden via Finland.

[7] The ship was boarded north of Iceland by the British navy and was brought to Kirkwall on the Orkney islands.

[9] He obtained a job as a receptionist at a London hotel, where he stayed until 1943 when he finally had the chance to return to Sweden.

[18] The duo also presented segments on television meant to educate men about cooking and cuisine, a task that had previously been considered a woman's duty.