In a sauté pan over medium-high heat, add butter and olive oil. Once the butter has melted add ground buffalo (or other meat) to the pan, using a spoon to break up any clumps of meat, cooking until there is no pink left and the meat is browned evenly. Remove meat from the pan into a bowl, leaving as much oil behind as possible. Add the carrots, onions, celery and leeks, seasoning with salt and pepper. Cook until the vegetables become translucent, about 5 minutes. Add garlic and cook for another 2 minutes. Sprinkle the flour evenly over the vegetables and cook for another 2 minutes. Add the reserved meat, thyme, parsley, and ale, scraping the bottom of the pan to remove any fond. Once the liquid comes to a boil, stir in the stock and bring back to a boil. Cook for 3-4 minutes, until the ale and stock form a gravy-like sauce. Check the seasoning.