For the gravy: Heat the oil in a skillet over medium heat. Add the garlic and the sausage, breaking up the latter with a spoon or fork and letting it brown until fully cooked. Transfer to a plate with a slotted spoon and set aside.
Add the onions and the butter to the skillet. Saute until the onions are dark brown and caramelized. Add the flour, a little at a time, and cook, stirring constantly, to make a dark roux, 6 to 10 minutes¿don't let it burn, but it should be nice and dark.
Slowly add the milk and beef stock, stirring vigorously to work it all together. Add salt and pepper to taste.
Add the cooked sausage to the gravy; stir well. Simmer for a minute or two, until the gravy reaches the desired consistency.
For the poutine: Fry the steak fries in vegetable oil until crispy.
Serve the fries covered in sausage gravy and cheese curds. Pop in the oven to melt the cheese curds, if necessary.