Combine flour, salt, and pepper in a shallow dish; dredge pork in flour mixture. Heat vegetable oil in a large Dutch oven over medium-high heat. Add pork and onion, and sauté 4 minutes. Stir in vermouth and broth, scraping pan to loosen browned bits. Add potato and remaining ingredients; bring to a boil. Cover, reduce heat, and simmer 40 minutes, stirring occasionally.