Which all are reasons why guests at Philadelphia District Attorney Lynne M. Abraham's annual holiday feast ooh, aah and cheer when she bears her regal beef on a fine china platter into her Center City dining room. It is a Norman Rockwell moment, one that Abraham eagerly anticipates each year, and has for, well, as long as she can recall.

Across the nation, home cooks turn to prime rib to celebrate the winter holidays or welcome a new year. Many do so because they ate this particular cut of meat throughout their childhoods at similar end-of-year celebrations. Others, like Abraham, did not have prime rib when they were growing up.

"My mother was the worst cook - not just in America, probably in this hemisphere," she says.

However, Abraham was seduced by Julia Child's television shows and books and, over the years after graduating from Temple University Law School, taught herself to make French sauces and stocks, to recognize salamanders (a type of French broiler) and mandolines (a kind of French slicer) and to know enough about meat to converse intelligently with the butchers at Harry Ochs' in the Reading Terminal Market.

Abraham is one of many Philadelphians who don't have to remind the Ochs butchers every year to set aside an aged, heavily marbled, prime rib roast for them. They have standing orders on the books.

Nick Ochs, grandson of the company's founder, estimates that the 100-year-old meat company sells about 500 rib roasts to Philadelphians in late December. (A whole standing rib roast has seven ribs, but roasts can be ordered with any number. They will accept Christmas orders up until the Sunday before.)

Technically, says Ochs, "one rib will serve two people, but one rib doesn't roast very well. You need at least two ribs for it to stand up in the roaster, allowing the fat to melt down through the meat as it cooks."

The best and most expensive standing rib roast is graded prime and has been aged for six weeks, says Ochs. This costs $18 a pound at Ochs'. If the meat is choice and has been aged only four weeks, it goes for $16 a pound.

Aging does three things: It breaks down some tissues to produce tenderness, and removes moisture and thus weight from the meat. It also gives the meat a blackened crust with patches of white.

Marbling, which means streaks of fat - not gristle - in the interior of the meat, determines its grade because where there is fat, there is flavor and tenderness.

A beautifully marbled, choice, whole standing rib roast aged for six weeks weighs about 18 pounds.

Abraham's standing order varies from four ribs, or about 10½ pounds, to two 5-rib roasts. Her dinner party, which is held between Christmas and New Year's Day, customarily has 10 diners, but some years she has a few more guests at the table.

Abraham doesn't believe in appetizers because they take the edge off appetites. Instead, she starts her meal with a first course of a very French sole mousse with tomato-cream sauce. She serves it with crisp white wine.

She says the dish is somewhat of "a pain to make, but I fell in love with it." She credits the recipe to Craig Claiborne, the late food critic, chef and writer, with Pierre Franey, published in a 1989 New York Times article headlined "How to Cook the Perfect Meal."

She reiterates, however, that Julia Child is her true muse, especially when she is able to prepare for dinner parties by starting reductions several days ahead of time.

She rounds out her holiday menu with Pommes Anna, another traditional French treatment for potatoes; a simple salad; and a free-form apple tart topped with crème fraiche or a bit of vanilla ice cream.

Abraham says she became enamored of prime rib for this dinner because, despite its kingly price and ability to impress, it is so easy to make. Basically, Abraham brings the meat to room temperature, coats it with a paste of salt, pepper, herbs, butter and flour, and pops it into the oven until it registers 130 degrees - medium rare - on an instant-read meat thermometer.

"I wanted something beautiful and elegant that doesn't take all day to prepare" because the potatoes, which are cooked just before serving, and the mousse and its sauce are so labor-intensive, says Abraham.

She begins gathering her ingredients two to three days before the dinner. She gets out the fine linen tablecloths and napkins, usable Philadelphia souvenirs that she purchased from the Bellevue Stratford hotel when it closed in 1976 as a result of Legionnaire's Disease.