This is a recipe I got from Americas Test Kitchen: Tastes real good.
Gravy from Almost Nothing
A top-notch, all-purpose gravy that can be made quickly without any special ingredients, including a roast.
Start with traditional mirepoix (a combination of carrots, onions, and celery) and brown well in butter to develop flavor and vegetable fond (the brown bits that stick to the pan). Add flour to form a roux, but cook it until it is the color of milk chocolate; this toasted roux provides an unexpectedly rich roasted flavor as well as a bold meaty flower. Use equal amounts of canned chicken and beef broths, and season with a classic combination of thyme, bay leaf, and peppercorns.
ALL-PURPOSE GRAVY Makes 2 Cups
This gravy can be served with almost any type of meat or poultry or with mashed potatoes. If you would like to double the recipe, use a Dutch oven to give the vegetables ample space for browning and increase the cooking times by roughly 50 percent. The finished gravy can be frozen. To thaw either a single or double recipe, place the gravy and 1 tablespoon of water in a saucepan over low heat and bring slowly to a simmer. The gravy may appear broken or curdled as it thaws, but a vigorous whisking will recombine it.
1 sm carrot, 1/2 inch pieces (about 1/2 cup)
1 sm celery rib, 1/2 inch pieces (about 1/2 cup)
1 sm onion, 1/2-inch pieces (about 3/4 cup)
3 Tbsp butter
1/4 cup all-purpose flour
2 cups low-sodium chicken broth
2 cups low-sodium beef broth
1 bay leaf
1/4 tsp thyme
5 whole black peppercorns
Salt and ground black pepper
1. In food processor, pulse carrot until broken into rough 1/4-inch pieces, about five 1-second pulses. Add celery and onion; pulse until all vegetables are broken into 1/8-inch pieces, about five 1-second pulses.
2. Heat butter in large heavy-bottomed saucepan over medium-high heat; when foaming subsides, add vegetables and cook, stirring frequently, until softened and well browned, about 7 minutes. Reduce heat to medium; stir in flour and cook, stirring constantly, until thoroughly browned and fragrant, about 5 minutes. Whisking constantly, gradually add broths; bring to boil, skimming off any foam that forms on surface. Reduce heat to medium-low and add bay leaf, thyme, and peppercorns; simmer, stirring occasionally, until thickened and reduced to 3 cups, 20 to 25 minutes.
3. Strain gravy through fine-mesh strainer into clean saucepan, pressing on solids to extract as much liquid as possible; discard solids. Adjust seasonings with salt and pepper. Serve hot.