For the last 26 years, Café Lutecia has thrived by the light of day. Its blue-awning-fringed corner has always been a beacon of toasty baguette morning rituals, homey French lunches sparked by Valérie Blum's secret vinegar, and the ultimate in tomato soup comfort, as well as its enduring draw as a community hub for longtime residents of Fitler Square.

So it was something strange, but also wonderful, to see its storefront windows ablaze with light and life when we arrived after dark recently for one of Café Lutecia's new Tuesday-night-only dinners.

A full moon hung over the 23rd Street sidewalk tables where diners at the BYOB toasted to summer with vintage pink Champagne (a very pretty Moët & Chandon 2008), and valiantly shielded their crocks of garlicky escargots and mini-paella pans from the occasional No. 7 and 12 buses that rumbled past.

"Goodbye to everyone I know!" came a soft voice from near the door as we slipped into our cramped marble table inside. It was the white-bearded artist Burnell Yow!, who didn't seem fazed in the least that few turned around as he left. One of the cafe's many fixtures (and also co-owner of the piano-playing YouTube sensation Nora the Cat), Yow! will be back, promised Valérie's husband and partner John: "He and his wife come four times a week. They love anything duck."

The Café Lutecia dinner party, meanwhile, was still rollicking in full force, basking in a decidedly different mood from what most guests were familiar with. Its long-established daily menu is rightfully well-loved, an array of toasty croque monsieurs, soulful soups (yes, the best tomato bisque in town), warm sandwiches with pâté and Brie or goat cheese and olives, or the anchovy-laced Provencale, or the fresh salads strewn with corn and hearts of palm that always remind me of visits to the homes of my French friends. John's croissant bread pudding, also available at night, should not be missed, either.

The dinners evoke a slightly different ambition - one steeped in the Basque-French tapas culture of Valérie's home in Biarritz.

An ever-changing short list of home-style plats du jour heat in the glorified toaster oven and a soup warmer in the tiny open kitchen, and a parade of little plates cover the entire wraparound counter with irresistible temptations. Sliced rounds of baguette from Parc are laden with simple combos, like Manchego with thin-sliced chorizo, garlic sausage with cornichon pickles and butter, tangy sardines with roasted peppers, or slices of Brie dabbed with Basque country black cherry marmalade.

The basic rules of Tuesday-night dinners can be hard to live by for patrons who've spent a quarter-century making themselves at home. But they also likely know, as they poke through the rustic bones and tender flesh of braised oxtails in a piquillo pepper sauce spiked with Armagnac, that these dinners are as much an experiment as a long-held dream come true. Not to mention a miracle.

Just a few years ago, Valérie, now 60, was gravely sick in the hospital, a cystic fibrosis survivor whose remaining lung was partially collapsed with an infection. But she recovered. And her subsequent participation in gene therapy at the Hospital of the University of Pennsylvania has given her a bold new breath of renewed purpose: "I feel like a new person now, and this cafe life keeps me going. I want to do more."

With encouragement and help from John and her youngest daughter, Jordane Blum, 27 (also a veteran server), they launched the dinners in March as a sort of pop-up. Would it lead to a larger new location? A renovation of the existing space?

They have no answers yet, though, as-is, with no ventilation for a real stove and just bare-bones equipment, this kitchen is extremely limited to dishes that can be precooked and reheated. In some cases it works, as with the big fresh Portuguese sardines she pre-grills over a barbecue. I can also still taste the garlicky chili oil of the head-on shrimp al ajillo roasted over a hot plate that glossed my fingers orange as I peeled the shells.

But in some cases it didn't pan out, as with the Basque take on bouillabaisse called Ttoro that brought a dry fish stew with overcooked hunks of monkfish, tuna, and mackerel that was a stretch for even lovers of the most rustic home cooking. I can also do without the mushy canned white asparagus - even if Valérie insists the fresh domestic variety doesn't taste quite right. Some other featured ingredients that Blum doesn't have the facilities to make, like the duck rillettes and truffled pâté from Les Trois Petits Cochons, are definitely still worth bringing in.

But for the most part, her menu is a testament to masterful efficiency and the delight of simple pleasures prepared with a knowing hand. I'm still thinking of the duck confit roasted crisp beneath mushroom sauce over fresh tagliatelle. Or how that braised oxtail's sauce melted into a bed of mashed potatoes. I also loved her mini-gratins, like the one with lightly creamed spinach or cauliflower in béchamel. Also adorable were the tiny croque madame squares ribboned with béchamel and ham and topped with a sunny-side up quail egg.

The cuminy spice of grilled merguez skewers with a side of cucumbers in tangy cream was irresistible, as were the mini-Spanish tortillas filled with mushrooms alongside an aioli. I will also devour any paellalike riff that somehow packs a taste of so many ingredients - big shrimp, clams, chorizo, saffron rice - into the cute comfort of a petit cast-iron pan.

I'd love to do that at home for a dinner party. I also hope someday to re-create the bracing freshness of her gazpacho shots - though I've already failed once. Yes, the woman has a magic touch with any soup. But Blum also has a secret weapon here: a stash of homemade vinegar fermented in an earthenware pot with a 100-year-old "mother" starter passed down through generations of her family. She secreted it here in a jelly jar from Biarritz, and the vinegar it creates from old wine - pungent, bright, and funky - may well be the subtle spark that's fueled 26 years of simple vinaigrettes that capture a certain je ne sais quoi and helped make Café Lutecia a beloved daytime gem.

As it now moves to embrace the night, too, even once a week and in a very different way, that same spirit is alive and thriving.

215-854-2682    @CraigLaBan

Cafe Lutecia

(two bells out of four)

2301 Lombard St.; 215-790-9557

After more than a quarter-century as a beloved Fitler Square hub for breakfast and lunch with a genuine French flair, this family-run corner cafe has launched Tuesday-night dinners featuring simple tapas and rustic plats du jour inspired by family recipes from owner Valérie Blum's home in the Basque country of France. The tiny space and under-equipped kitchen limits what can be done, but the best dishes are homey in a good way, and the experience as a whole, fully embraced by its devoted fans, offers hints of an intriguing new chapter for one of Center City's most charming and enduring neighborhood gems.

MENU HIGHLIGHTS Breakfast and lunch: tomato soup; chicken peanut soup (all soups, really); toasted baguette with tomato and brie; croque monsieur; sandwiches (pâté and brie; garlic sausage and pickles; Gaulois; le Chevre; Provencale); salads (Provence; Gauloise); quiche Lorraine. Dinner (changes often): mini-croque madame; Serrano and chorizo; merguez; escargots; grilled sardines; rillettes de canard; mini-paellas; grilled garlic shrimp; duck confit with mushroom tagliatelle; Basque oxtail stew; croissant bread pudding.

IF YOU GO Breakfast Tuesday through Friday, 7-11:30 a.m.; Saturday and Sunday, 8-11:30 a.m. Lunch Tuesday through Sunday, 7 a.m.-3 p.m. Tuesday-night dinners, 6-9 p.m.

Lunch entrees, $6.25-$11. Dinner plates, $13-$21.

All major cards.

No reservations.

Not wheelchair accessible. (Two steps at the entrance, and bathroom is not accessible.)

Street parking only.