Remove the roast from the marinade (reserve the liquid).
Heat vegetable oil in a Dutch oven or heavy skillet over medium heat.
2 tablespoons vegetable oil
Sear the roast on all sides until browned.
Place the seared roast in the slow cooker.
Add the reserved marinade, the remaining 32 ounces of beef broth, onion , carrot chunks, and smashed garlic cloves.
32 ounces beef broth, 1 onion, 1 carrot, 4 garlic cloves
Add freshly ground black pepper.
Cover and cook on low for 8–10 hours or high for 5–6 hours, until fork-tender.