Shake vodka, Becherovka, Kummel, and lime juice with ice. Strain into mule mug or double rocks glass. Add ginger beer and ice to fill. Garnish with lime wheel or wedge. Serve with straw.
I wanted to create a distinctive mule with Polish Żubrówka, and Przewalski's horse came to mind, which is named after Russian explorer/geographer/officer Nikolay Przhevalsky. He was born in Russia to a family of Polish nobility. Becherovka and Kummel fill out the west Slavic character of the concoction, providing cinnamon and caraway notes respectively.
While a distinct species, Przewalski's horse (pronounced shuh-VAL-skee) can crossbreed with domesticated horses despite having 66 and 64 chromosomes respectively. The offspring look like a Przewalski's horse, can reproduce, and can be distinguished through genetic tests. I do not know if the P-horses can interbreed with donkeys (the latter having only 62 chromosomes).