Saehrimnir

Saehrimnir is a magical beast that stays in Hotel Valhalla. Everyday, it is killed and cooked for dinner and every morning it is resurrected. Its meat tastes like whatever the diner wants.

The Sword of Summer
Samirah al-Abbas mentions Saehrimnir to Magnus Chase at Hotel Valhalla. This happens at dinner time on Magnus' first day at the hotel when Sam is giving him an orientation of the place. Sam mentions that the beast's meat can turn into whatever food the diner prefers. She gives her example, saying that the meat won't be pork for her. (Being a devout Muslim, Sam doesn't eat pork.)

Magnus asks whether Saehrimnir's meat can make vegetarian items such as falafel. Sam is surprised by the word 'falafel' because it reminds her of her fiance, Amir Fadlan, who runs a falafel shop with his father.