Season the beef short ribs with salt and black pepper. In a large skillet, heat some oil over medium-high heat and sear the short ribs on all sides until browned. Remove and set aside.

Make the Braising Liquid

In the same skillet, add chopped onion and minced garlic. Sauté until soft and fragrant. Add root beer, beef broth, soy sauce, and brown sugar. Stir to combine.

Braise the Ribs

Return the seared short ribs to the skillet with the braising liquid. Bring to a simmer, then cover and transfer to a preheated oven at 300°F (150°C). Braise for about 3 hours, or until the meat is tender and falling off the bone.

Prepare the Mashed Potatoes

While the ribs are braising, peel and chop the potatoes. Boil them in salted water until fork-tender, about 15-20 minutes. Drain and mash with butter and milk until creamy and smooth.

Cook the Vegetables

Prepare the vegetable of your choice by steaming, sautéing, or roasting it as preferred.

Serve

Once the short ribs are done, remove from the oven and let them rest for a few minutes. Serve the short ribs on a plate with mashed potatoes and the vegetable of the moment.