Spoon off all but 2 1/2 tablespoons of the fat from the skillet. Stir in the onion and cook until tender, about 3 minutes. Stir in the garlic and cook until fragrant, about 1 minute. Add the black beans, chicken stock, Canadian bacon and bay leaf and stir well. Bring to a simmer and cook over low heat until the liquid has thickened, about 20 minutes. Stir in the red wine vinegar and season lightly with salt and pepper. Ladle the stew into bowls and serve.