Preheat the oven to 300˚F.
In a heavy braising pot or Dutch oven, heat a drizzle of oil over medium-high heat and brown the beef in batches, sprinkling with salt and pepper.
Once the meat is all browned, return it all to the pot and sprinkle with the flour, stirring to coat.
Add the stock, wine or beer until the liquid almost covers the meat.
Add the balsamic vinegar, tomato paste (if using) and toss in a sprig of rosemary from the stew mix package.
Cover and bake for 2 hours, then stir in the stew mix and return to the oven (covered or uncovered, if you’d like it to thicken a bit) for another half an hour, until the vegetables are tender.