One of my favorite holiday memories is of standing at my mother’s elbow, watching her make beef gravy from a rib-eye roast. This cut of meat often was the centerpiece of our Christmas dinner, and we always had ample gravy.

When I tried making this gravy on my own, without her there to coach, I realized that this had been no small feat, even though my mother had made it seem so effortless.

Her gravy was always made from pan drippings and directly in the bottom of the roasting pan. There, the flavors of the meat and the herb and garlic rub that she applied prior to roasting had merged and condensed. After the roast had cooked and while it rested prior to carving, she placed the roasting pan over a stove burner set to simmer and went to work using a flat whisk, a flour roue, milk, a splash of red wine and salt and pepper.

This memory was rekindled this week when I received an e-mail from a reader who wanted advice on cooking times for a boneless prime rib. My first thought was that my mother would have known the answer. Some habits of mind from early in life are hard to unlearn.

I’m probably a bad person to ask about either the bone-in prime rib, also known as a standing rib roast, or the boneless version because I’m no fan of rare beef. What I would consider an appropriately cooked roast most people would think was overdone. When my mother cooked a roast for Christmas, I always asked for a piece cut near the end.

Anyway, the reader’s concern was that the deboned prime rib roast her family ate last Christmas turned out to be “just slightly overdone.” She had cooked it for 15 to 18 minutes per pound and wondered whether she should lower the cooking time this year and, if so, how much. She asked whether I knew of a formula for determining this.

Even for someone like me, who doesn’t like rare beef, overcooking a cut like the rib roast can dry it out. So even I recognize this as a problem, while at the same time I might prefer to err in the direction of doneness. Therefore, my approach always has been to shoot for medium rare, with emphasis on the medium.

As I researched my reader’s question, hoping to find information that would be useful to people who liked their roasts rarer than I do, I found near universal agreement on one point: A rib roast should be brought to room temperature before it is placed in the oven.

I found no agreement on suggestions for rubs and marinades. In fact, some of the recipes I encountered likely would ruin the meat. Given the cost of a rib roast, do-overs aren’t usually allowed. In this group of bad ideas, I would include recipes that used regular table mustard, tomato paste and vinegar.

My personal favorite roast rub is a simple paste made of pressed garlic, salt and pepper. Rather than mix in herbs, I lay a couple of sprigs of fresh rosemary in the roasting pan.

The important piece of information, though, is that doneness should be determined by the internal temperature of the meat, not the cooking time. While cooking time can be estimated to help you stay on schedule, the thermometer is the last word on doneness.

The reader was correct that 18 minutes per pound is a rule of thumb for a roast in a 325-degree oven; however, the optimal internal temperature for a roast that is medium rare in the center appears to be 130 to 135 degrees.