Sprinkle pork with salt and pepper; add 3 tablespoons flour and toss to coat. In a large skillet, heat oil over medium heat. Brown pork. Drain if necessary. Stir in vegetables, broth, garlic, mustard and thyme. Bring to a boil. Reduce heat; simmer, covered, until pork and vegetables are tender, 10-15 minutes.
In a small bowl, mix remaining flour and water until smooth; stir into stew. Return to a boil, stirring constantly; cook and stir until thickened, 1-2 minutes.