Heat the olive oil in a large pot over medium heat. Add the pork cubes and brown them on all sides, about 6 to 8 minutes total. Remove the pork and set it aside.
Add the diced onion to the same pot and cook until softened, about 4 minutes. Stir in the minced garlic and dried oregano and cook for 1 minute more.
Pour in the diced tomatoes and chicken broth. Return the browned pork to the pot and season with salt and black pepper. Bring the mixture to a simmer.
Cover the pot and cook on low heat for 45 minutes, stirring occasionally, until the pork is tender.
Stir in the halved Kalamata olives and cook uncovered for 5 more minutes to warm them through. Remove from heat and sprinkle with the fresh chopped oregano before serving.