1. In a large cast-iron skillet, heat oil over medium-high heat. Add onion and sauté until it starts to brown, 5 to 8 minutes. Add potatoes and cook, stirring, until they brown in spots and become crusty, about 8 minutes more. Stir in corned beef and broth and cook, scraping up any browned bits, until liquid is absorbed, 5 to 8 minutes. Add parsley and season with salt and pepper.
2. Meanwhile, fill a large skillet with 2 inches salted water and bring to a gentle simmer. Break eggs, one at a time, onto a saucer and slide into the simmering water. Poach eggs until set to desired firmness, 4 to 5 minutes.
3. Divide hash among 4 plates. Place eggs on top of hash.
