Into each life, the saying goes, a little rain must fall. Likewise, despite our best efforts, another dreaded phenomenon is bound to strike: the weeknight dinner guest. It may be your college roommate in town for a business meeting or a cousin and her husband driving through. Of course, you are delighted to see him/her/them, but your workday is infused with panic. How in the name of all that is holy are you going to get the house in some semblance of order and get a more-than-decent meal on the table?

Enter the pork tenderloin. This cut of meat came to our attention in the early 1990s, when low-fat eating became de rigueur. The pork tenderloin is, in fact, a lean piece of meat; it has slightly fewer grams of fat than a skinless chicken breast and qualifies for the U.S. Department of Agriculture’s “extra lean” status. But more than that, the pork tenderloin cooks quickly, making it a wonderful, easy, last-minute kind of meal. And it dresses up well with marinades and sauces.

Pork tenderloin comes from the pork loin, which is between the shoulder and the leg. This most tender part of the pig gives us chops, whole roasts, Canadian bacon and baby-back ribs. The tenderloin is located just above the spare ribs. One-pound tenderloins are often, but not always, sold in packages of two; you may find your store packages tenderloins separately, and each weighs about 1-1/2 pounds.

Pork tenderloins can be cut up for kebabs or stir-frys, cooked quickly on the stovetop or grill or in the oven, leaving you plenty of time to vacuum the living room.

A new cookbook, “Organic Marin” by Tim Porter and Farina Wong Kinsley (Andrews McMeel, 2008), includes a delightful recipe for grilled pork loin with nectarines that would wow any guest. The other recipes here come from the excellent “Niman Ranch Cookbook” by Bill Niman and Janet Fletcher (Ten Speed Press, 2005).

Food-safety note: Food-safety experts recommend cooking pork to an internal temperature of 160 F, which kills salmonella. (Trichinae, the parasite that causes trichinosis, are killed at 137 F.) Chefs recommend it be cooked, for taste and tenderness, to 150 F. The choice is up to you. Remember that when you let meat rest after cooking, it will continue to cook, and the internal temperature will rise at least 5 F.

GRILLED PORK TENDERLOIN AND NECTARINES WITH BACON VINAIGRETTE

For the vinaigrette:

3 ounces diced pancetta (Italian bacon) or thick-sliced smoked bacon

2 tablespoons minced shallots

1/2 teaspoon brown sugar

1/2 cup red-wine vinegar

1/2 cup extra-virgin olive oil

1/2 teaspoon salt

1/4 teaspoon freshly ground pepper

For the pork:

1-1/2 pounds pork tenderloin, trimmed of fat and silver skin

2 firm nectarines, quartered (pits discarded)

1 to 2 tablespoons canola oil

salt and freshly ground black pepper

1 head frisee lettuce or small bunch arugula

Prepare a gas or charcoal grill for direct grilling over high heat. If using a charcoal grill, make sure that you arrange the coals so there is a low-heat area. If using a gas grill, be prepared to shut off or turn down one or more of the burners.

Make the vinaigrette: Heat a small skillet over medium heat, and cook the pancetta until golden, at least 3 minutes. Add the shallots, and saute for 2 minutes. Remove the pan from the heat, and stir in the sugar and vinegar. Gradually whisk in the olive oil, then the salt and pepper. Set aside until ready to serve.

Season the pork and nectarines generously with oil, salt and pepper. Place the pork and nectarines on the grill and sear for about 5 minutes, or until both are browned on all sides. Make adjustments so the meat and the fruit are cooking over low heat (i.e., move the food to a cooler part of the grill, or turn one or two burners down or off). Cover the grill, and cook until done to your liking, at least 12 minutes. (See food-safety note above.)

Reheat the vinaigrette over low heat. Lightly dress the frisee (or arugula) with some of the vinaigrette, and mound on a platter or four individual plates. Cut the pork into 1/2-inch thick slices, and place with the nectarines alongside the salad. Drizzle with the remaining vinaigrette and serve.

Yield: 4 servings

Recipe from “Organic Marin” by Tim Porter and Farina Wong Kingsley (Andrews McMeel, 2008)

CHIPOTLE AND CITRUS-MARINATED PORK TENDERLOIN

2 pounds pork tenderloin, trimmed of fat and silver skin

1 cup orange juice

6 tablespoons fresh lemon juice

6 cloves garlic, smashed and peeled

2 shallots, peeled and chopped

2 dried chipotle chilies, crushed into small pieces (see Cook’s note)

1 tablespoon olive oil

kosher salt and freshly ground black pepper

3/4 cup chicken broth

2 tablespoons chopped fresh cilantro

Cook’s note: Chipotle chilies are smoked jalapenos. They are often sold in adobo sauce in a can in the Hispanic foods section of the supermarket and often sold dried, in cellophane packages. If you can’t find them dried, scrape the adobo off a canned chipotle and use that, chopping it first. The canned chipotles in adobo are very potent; one will probably do the trick.

Set the meat in a nonreactive baking dish. Combine the orange juice, lemon juice, garlic, shallots and chilies in a small bowl, and stir well. Pour over the pork, and let sit for 20 minutes at room temperature.

Preheat the oven to 400 F.

Heat the oil in a large, ovenproof skillet over medium-high heat. Remove the pork from the marinade, reserving the marinade. Wipe the pork dry with a paper towel, and season with salt and pepper. Add to the skillet and cook, turning as needed, 4 to 5 minutes, until evenly browned. Transfer the skillet to the oven, and roast for at least 15 minutes. Check internal temperature until it is done to your liking. (See food-safety note above.)

Transfer the tenderloin to a plate, and cover loosely with aluminum foil to keep warm.

Pour the marinade into the skillet, and add the chicken stock. Bring to a boil over high heat, and cook for 8 to 10 minutes, until reduced and thickened. Pour through a fine mesh sieve into a bowl.

Cut the tenderloin across the grain into thin slices, and arrange on a platter. Drizzle the sauce over the top, and sprinkle with cilantro. Serve.

Yield: 6 servings

Recipe from “The Niman Ranch Cookbook” by Bill Niman and Janet Fletcher (Ten Speed Press, 2005)