Heat a frying pan over medium heat and lightly brown the sausages on all sides. This step is optional but adds extra flavor and color to the finished dish before transferring the sausages to the slow cooker.

Place the sliced onion, carrots, potatoes, and garlic into the slow cooker around the sausages. The vegetables will absorb the curry flavors as they cook and become perfectly tender.

In a bowl, whisk together the beef stock, curry powder, tomato paste, Worcestershire sauce, brown sugar, salt, and black pepper. Mix until smooth and fully combined.

Pour the curry mixture evenly over the sausages and vegetables in the slow cooker. Ensure everything is well coated so the flavors distribute evenly during cooking.

Cover and cook on LOW for 6–8 hours or HIGH for 3–4 hours until the sausages are cooked through and the vegetables are tender. The curry gravy will become rich and flavorful as it simmers.

Mix the cornstarch and water to create a slurry, then stir it into the slow cooker during the final 20 minutes of cooking. Once the gravy has thickened, serve the curried sausages hot with rice, mashed potatoes, or crusty bread.