Mimi Chryssikos spent her childhood cooking with her French mother and Greek father. Among her duties was drying the lettuce with an apron on their back porch in Uptown. She has a catering business. She is strongly against ketchup.

But no one in Mimi’s Specialty Deli on the last Saturday in March cares about any of that. The only thing they’re concerned about is whether there will be enough croque madames to go around. It’s her last day in business, and some of the regulars are just finding out.

“Oh no!” says the woman ordering a Latin panino. “Well, how long are you open today?”

“Five, or when I run out of stuff,” Chryssikos says placidly.

Chryssikos and her partner, Andrew Given, opened their deli on Montrose near Damen four years ago; before that they had sold marinades and salad dressings over the Internet. Mimi’s got smashing reviews, and customers started heading to Ravenswood from the Gold Coast and Lincoln Park. Still, walk-in traffic was never quite steady enough. After their fourth anniversary–September 11, 2001–it just got worse.

“Some things aren’t meant to last forever,” says Chryssikos. She’s warning another customer about the limited shelf life of her Citronnette, a lemon vinaigrette dressing with a bright, clean, picnicking-in-Europe taste. “If you want that, go buy Thousand Island.”

Today, as usual, the service is friendly but slow, because the food isn’t made until you order it, and you get it when it’s ready. Chryssikos and Given have never had any employees. Furthermore, the customer is not always right. But the regulars understand this. A woman in line asks her husband, “What are you getting?” and he replies, “I don’t know. Whatever Mimi said.”

Given brings out a croque madame, served on a square purple plate with a salad–leaf lettuce, vivid carrot shreds, bright red pepper, and snips of cool green onion. Chryssikos makes her croques with bechamel sauce, perfectly golden, just barely spilling over the edge. It’s a sunny, windy day, and the door is open. Everything on the plate tastes like spring.

Chryssikos and Given greet every other customer by name: “Hi, Maggie. I have your Citronette. I don’t know if you want one or two; I made ’em anyway.” A little girl named Fiona asks “Ca va, Mimi?” and requests some chocolat. She does not get it until she has finished her lunch, when she comes behind the counter and gives Chryssikos a kiss. A man comes in and presents Given with an umbrella; he thanks him, puts it behind the counter, and goes on working. Chryssikos asks, “Did we make coffee?”

Given met Chryssikos when she was working in a French pastry shop, where she was using her homemade salad dressings in the sandwiches. He had majored in entrepreneurship at DePaul, and they started talking about how to market the dressings. In the process she taught him how to cook; he taught her how to sell.

They’ve talked to everyone from Kraft to Dean & DeLuca about getting the dressings to a wider market. But Chryssikos won’t use preservatives, and as Given says, “If it can’t sit on the shelf for two years, they don’t want it.” He spends a lot of time finding wholesalers who will sell him small quantities of the right bottles, and the labels are in her handwriting. They’re hoping to find investors who understand their commitment to–and insistence on–quality ingredients, small batches, and disdain of shortcuts.

After July 1, Chryssikos will be working at the Long Room on Irving Park, making hot and cold sandwiches for the bar, and continuing to cater. “When in doubt, marinate,” she says. Given is thinking about becoming a day trader downtown or going into product development. They’ll still be talking to investors, and they’ll still be selling products on the Web site (www.givmi.com).

The menu shrinks as the day goes on. “I have salami, I have turkey, I have ham, I have goat cheese,” says Given to a customer. “Do you like goat cheese? We can do a French panini.” A man comes in to extend his condolences and stock up on dressing. Chryssikos has been talking and cooking all day, but she doesn’t look tired at all. “Hi, Robert,” she says. “How are you?” “Hungry.” This is what she likes to hear, and she goes on slicing and spreading.