Making a roux is about browning flour in a fat to use as a thickening agent. You want to do it on the lowest possible temperature and expect it to take a while. If black flecks appear in your roux, that means that you have started to burn it and need to start over. I use roux as a starter for brown gravy to go with things like a Philly sandwich, as a starter in my gumbo, and in a few other applications. Think about the flavor of the oil you are using compared to the dish you are making. I use butter in my roux when I am making a gravy for a Philly sandwich, and I usually use bacon lard for my roux base if I'm making gumbo. Recipes, if you are following one, will usually tell you the ratio that they want you to use for your recipe to give you the ideal thickened amount for your dish. However, a general rule of thumb is equal parts by weight of oil to flour. This equates to slightly more flour, as flour is not as dense and heavy as oil. To make a roux, select the oil of your choice with flour and grab a whisk; start by warming and melting the oil (if solid like butter) at the lowest temperature possible in your pan. Once it is melted, and it should not be bubbling, dump your flour in. Raise up the temperature just slightly and keep stirring. Whisk, whisk, whisk the hell out of it. You want it to ever so slightly bubble so play around with your temperature to get it right where it needs to be. It may take as long as 30 minutes to fully brown your roux. Don't get impatient. There isn't really a shortcut. You can take breaks in the whisking but don't let it stick to the bottom and don't let it bubble too hard. It will very slowly start to change from a tan color to a light brown to a deep mahogany. You want to get it fairly deep Brown, and when it gets there you're all done. Make sure you remove it from heat to stop the cooking process and stir a little more to keep it from sticking to the bottom. It's now ready to use. If I'm using my little bit of roux for a gravy, I then add water with some beef bullion or even a little bit of beer for flavoring. If I am going to use the roux for a gumbo, this is the part where I dump in all of my chopped vegetables like celery bell peppers and onions and mix it around so that the roux is evenly covering all of the vegetables.
What kind of gravy are you using for a Philly sandwich? Are you talking about a Philly roast pork sandwich with broccoli rabe and sharp provolone?
Oh baby, yes. I make several variations in terms of meat (typically beef or chicken) but there are always fuckloads of onions and peppers, usually provolone, sometimes mozzarella, sometimes mushrooms, and I get one of those French bread loafs from the grocery deli for a buck and heat it in my oven for 8min to make it taste like oven fresh bread. That's my kitchen cheater tip of the day. Bake the stuff from the grocery store and it tastes like you just baked it FROM scratch.
When you fry bacon, which should be a regular part of your diet anyway, use the grease to make a roux for white gravy. Serve this over biscuits (store bought is fine but buttermilk biscuit recipes are easy to find and easier to follow). Makes me hard just thinking about it.
Yes, I save all bacon grease and it is stored in a glass pickle jar in my fridge door. It makes great roux and makes caramelized onions taste better. I usually make biscuits and gravy with butter considering I put sausage in it, but I'll have to try it with bacon grease.
I know this is a little off topic, but frying eggs in bacon grease is the only way to go. As for the bacon grease roux, I've used this to thicken the cajun chicken pasta that Blue Dog posted in the other thread and it was awesome.