In a large bowl, season pork with salt and pepper. In a large pot over medium heat, combine pork, onion, garlic, broth, cumin seeds, and bay leaf. Add enough water to cover pork by 2". Bring to a boil, then cover, reduce heat to medium-low, and bring to a simmer. Cook, skimming foam off top as needed, 1 hour 30 minutes.
Meanwhile, in a medium heatproof bowl, soak chiles in 2 cups boiling water for 30 minutes.
Transfer chiles and about ½ cup soaking liquid to a blender. Blend until smooth, adding more water as needed.
Add chile puree and hominy to pot with pork. Cover and continue to simmer, stirring occasionally, until pork is very tender, about 1 hour 30 minutes more; season with salt and pepper.
Top pozole with radishes, cabbage, and cilantro.
