In large bowl, combine pork, all-purpose flour, salt and black pepper, and toss well to evenly coat pork.
Add oil to large pot and heat on medium-high heat. Once oil is hot, add cubed pork, and sear for 5 to 8 minutes or until browned, stirring often. Once pork is seared, remove from pot with tongs and set aside on plate.
Reduce heat to medium, and add chopped celery, onion, garlic and carrots to pot. Cook for about 3 to 5 minutes, or until veggies are tender, stirring often.
Add in tomato paste and stir it in with veggies with wooden spoon, then add beef broth, fresh thyme and rosemary. Return seared pork to pot with veggies, and stir well.
Bring stew to boil, then reduce heat to low, and let simmer uncovered for about 45 minutes, stirring occasionally, until stew has thickened. Serve warm.