Here's how to make a simple, American style gravy
1-1/2 cups stock, can be beef, chicken, or combined when siding pork or veal
1/2 cup dry red wine for beef stock or white wine for chicken
2 tbs butter
1 tbs + 1 tsp flour
1 tsp extra virgin olive oil, corn oil, or other cooking oil
2 tbs (additional) butter
1 cup sliced mushrooms; and/or
1/2 cup thin sliced onions
In a sauce pan, combine the stock and wine. Bring to a boil, reduce the heat to a simmer and cook until the wininess cooks off, and the mix reduces to about 1-1/2 cups total. Set the stock aside.
If you'll be using the mushrooms or onions: Preheat a skillet to medium hot. Add the oil, when the oil is hot add the butter. As soon as the butter melts (which it will do very quickly) add the mushrooms and/or the onions. Allow to cook without shaking, turning or moving for at least three minutes, and turn (by tossing if you know how). Cook until fully softened. Set aside.
Make a roux with the butter and flour as follows: Add the butter to the sauce pan, melt the butter over medium heat. When the butter has melted, add the flour. Cook the raw off the flour (about three minutes). If you like, you can continue cooking until the flour just starts to brown (about eight minutes).
Return the stock/wine mixture to the pan along with the roux. Turn the heat up, and bring to a boil. Immediately reduce to a simmer and hold at the simmer for at least five minutes in order to get full incoroporation of the roux and maximum thickening. Pass the sauce through a sieve, add the mushrooms and/or onions if you're using them, and hold over very low heat until required.
Hope this helps,