General Description: Beef marrow is the delectable soft fatty tissue found in the center of animal leg bones. Considered a delicacy in many countries, especially in Europe, marrow is rich, expensive, and quite perishable. Knuckle bones and other gelatin-rich beef bones are desirable for making soup, stocks, and sauces because they impart flavor and body, especially important in a reduction (sauce that is cooked until thick). Roasted marrow bones are a French bistro specialty.

Part of Animal: Marrow bones are straight portions of leg bones that contain marrow. Knuckle bones connect the leg bones; neck bones are vertebrae from the neck.

Characteristics: Fresh marrow has the consistency of hard butter and is whitish, with red streaks of blood and nerves.

How to Choose: Beef leg bones, cut in 2- to 3-inch sections, can be used for their marrow. Marrow is also sold by weight by special order at butcher shops or from wholesale meat purveyors, and it is usually frozen. Fresh or frozen knuckle or neck bones are best used for soup, stocks, and sauces.

Amount to Buy: Buy 1 pound of marrow bones per person. To make it easier to extract the marrow, buy vertically cut bones. Allow about 8 ounces per person. Allow about 2 ounces pure marrow per person. For soups and stock, buy at least 5 pounds marrow, knuckle, or neck bones.

Storage: Keep soup bones refrigerated and use within 2 days of purchase, or freeze. Refrigerate pure marrow soaked in cold water mixed with salt and use within 2 days.

Preparation: Marrow:

1. Soak 2- to 3-inch sections of marrow bone in tepid water for about 2 hours.
2. Push the softened marrow out of the bone and discard the bones.
3. Refrigerate the marrow overnight in a bowl of ice water mixed with salt to extract any blood.
4. Cut into slices 1/2 inch thick.
5. Poach the marrow slices in salted, boiling water 1 to 2 minutes, then drain.
6. Sprinkle each slice with salt, chives, or parsley and use to top beef, veal, or fish.

Flavor Affinities: Chervil, chives, fleur de sel, garlic, green onion, herb butter, lemon, paprika, parsley, salt, tarragon.