Heat the olive oil in a large pot over medium heat. Add the pork cubes and cook until lightly browned on all sides, about 5 minutes. Remove the pork and set it aside.
Add the onion to the same pot and cook until softened, about 3 minutes. Stir in the garlic and cook for 1 minute more.
Return the pork to the pot. Add the potatoes, chicken broth, salt, and pepper. Bring the mixture to a simmer.
Cover and cook for 15 minutes, stirring occasionally, until the potatoes begin to soften.
Add the green beans and continue simmering for another 10 minutes until the beans are tender but still bright.
Stir in the lemon juice, lemon zest, and fresh oregano. Simmer for 2 more minutes, then remove from heat.