She’s a peripatetic gourmet, an epicurean, and a culinary bon vivant—but she didn’t know how to cook. Until now. In the first column of an ongoing series, Reggie Nadelson seeks help from a real master of the kitchen.

Early in the morning the foggy sunlight glints off the Thames through the large windows of the River Café. A guy is folding piles of starchy white linen, the chefs are starting lunch, and I’m up to my elbows, metaphorically at least, in tomato sauce. Ruth Rogers, the co-owner (with Rose Gray) of this London restaurant—which arguably serves the best food in town—is teaching me how to make pasta. "We’re very fussy about seasonality here," says Ruthie, which is what everyone calls her. "You never want to use tomatoes unless they’re absolutely in season and perfect, and then you would just blanch them, peel, take out the seeds, chop them up…." And it’s here that my eyes begin to glaze over like something suspended in aspic. I wonder if I can get an appointment for my nails later or if there’s something useful I can do for, say, the Peace Corps. I don’t do blanching. I don’t peel things or take out little seeds.

Maybe it’s genetic. My Canadian grandmother’s idea of cooking was to put the meat in the oven until it was more or less gray. My mother, who lived in New York City, did not spend a lot of time in the kitchen cooking up stuff for my memoirs; mostly she made reservations. I don’t cook because I never saw the point. In Manhattan and London I live in neighborhoods (SoHo and Notting Hill, respectively) that are dense with food shops. You can hardly leave the house without tripping over places that sell fresh pasta and bread, mozzarella smoked on the premises that morning, exotic fruit all year, gorgeous lemon tarts, perfectly cured prosciutto. And when I’m alone at home and hungry, I reach for the takeout menus. But one dank, dark night I found myself yearning for a bowl of spaghetti. And eating takeout pasta is like trying to swallow rubber bands dunked in glue. In the back of the kitchen cupboard I discovered an old bag of penne left by friends probably about ten years ago. I added some antique clams from a can. Here is where things always go wrong. What do they mean by "rapidly boiling water"? How rapid and why do I seem to need enough to boil an old hen? The dish was not a success. I considered my options. My favorite pasta is the tagliatelle al pomodoro at the River Café. The stuff is so good that it’s what Ruthie cooks at home for her husband, Richard (Lord Rogers, the architect), and what friends like Bernardo Bertolucci always order at her restaurant. "Of course, darling. I’d love to be your first tutor," Ruthie says. "Come in next Tuesday morning." On the appointed day I creep out of my flat in London, where I spend part of the year, and into a taxi. When I arrive at the restaurant, a young chef named Joanne is braising savoy cabbage to be served with chestnuts and pancetta alongside some partridge. Other people are doing magic with crabs (for a risotto), baby red mullets (for a fritto misto), and aromatic porcini. I’m scared of tomato sauce. "Okay, first we’ll coat the frying pan with olive oil, put in slices of garlic, and cook them until they’re transparent," says Ruthie, a woman with startling blue eyes who was born in New York and still has an American accent after 30 years here. The River Café was once the canteen for Richard Rogers’s practice, which now sits just across the courtyard so you can see the architects at work as you dine. On weekends during lunch the place feels like a kind of club; people bring children and grandkids and roam around the room greeting friends. The last time I was here I sat next to Hugh Grant as he read the paper and indulged in the restaurant’s most famous desert: Chocolate Nemesis. The kitchen is working full blast now, but Ruthie patiently watches me fiddling with the garlic. "Go ahead, just push them around," she says. A guy from FedEx arrives with a Tupperware box from Piedmont, Italy. It contains a big, fresh white truffle. We all gather around for a reverent sniff, as if FedEx has just delivered the Holy Grail. I love food. I love eating it, looking at it, reading and writing about it. In Paris there’s no bakery too remote, in Brooklyn no pizzeria too far. I like people who work in restaurants and food stores, their congenial obsessions. Once I met a guy from a Bangladeshi cheesemaking family who sold cheese at Dean & DeLuca in New York. I was delighted to learn that they even made cheese in Bangladesh. Ruthie is still watching me push around the garlic. She tells me again to cook it until it’s transparent. Then, thrillingly, she hands me a jar and says, "The thing is, unless they are really in season, you don’t want to use fresh tomatoes. It’s much better to use good tomatoes in jars or cans." Really? Cans? Yes, she tells me, the kind where nothing has been added except the juice of the fruits themselves. Tomatoes—she uses San Marzanos—in their own juice, with more pulp than skin. As for the pasta, unless you get the stuff made fresh that day, she says, buy it in a box or a bag. Cans? Jars? Store-bought packages of De Cecco pasta? I’m on my way. I dump two jars of tomatoes into the frying pan with the oil and garlic.

She hands me a big spoon and says, "Stir some more. The really important thing," she adds, "is that you have to let it cook very slowly, maybe an hour." She sees my expression. "But you can use it for four days. And if you want something really rich, you can add a lump of butter to the sauce just before you eat it. Now for the pasta."

This is the thing I dread, the rapidly-boiling-water moment. Just turn the heat up, Ruthie tells me. Just be a little bit patient, she says. Meanwhile, place the colander in the sink, she instructs. Inside our large pot, the boiling water dances around in ways it has never done for me before. I throw in some salt, then put in the tagliatelle. After a few minutes Ruthie reaches in with a fork and we each sample a strand. Al dente, but not too. I’m getting the hang of this. Being with a pro in the kitchen makes me confident. "Drain the pasta in the colander, then put it into the pan with the sauce," she says. I like this. "Okay," Ruthie continues with an ecstatic expression. "This is the trick. You put the pasta in the pan and you toss, toss, toss until the strands are not just coated but infused with the sauce." I place it on a large white plate that somebody has warmed. Ruthie pours on a little of the extra-virgin olive oil—the really good stuff—over it and hands me a fork. Several of the young chefs gather around. Joanne smiles encouragingly. This is like singing in the shower and discovering you’re actually on stage at the Met. "That’s it?" I ask. "That’s it," Ruthie says. "Eat." I eat. It tastes like a platonic version of pasta with tomato sauce, the quintessential thing itself. It doesn’t need any more adjectives. And I made it, more or less. My white jacket and apron are splattered with red tomato sauce like splashes of fresh blood. At the River Café in London, over a dish of pasta, I’ve lost my virginity.