BY RICHARD CHACON
 The Boston Globe

 ZACATECAS, Mexico -- Joanna and Catalina Herrera, the co-owners of a small
 luncheonette in this central Mexican city, swear it has more healing powers than
 chicken soup. And Gerardo Luna, a state government employee, says that when
 prepared as a tea with anise and pepper, it can ``raise the dead.''

 The secret? Rats.

 ``It sounds awful, even to many of us,'' said Joanna, 32. ``But the truth is they
 taste very good and they're good for you.''

 Boiled in a soup, grilled over an open pit or mixed in a stew, rats are more than
 just a nuisance to be chased with a broom. They're also a delicacy and a tradition
 here that has been passed from indigenous ancestors to computer programmers.

 They aren't your run-of-the-mill gutter rodents, but their country cousins, the field
 rat. The difference, connoisseurs say, can be detected by the field rodent's longer
 torso -- much like a small squirrel -- light brown pelt and shorter tail.

 But it's still a rat, with a rat's bad public image, which might explain why none of
 the local restaurants features such dishes on their menu.

 BIG DEMAND

 ``It's not something people would want to see on a menu, especially the tourists
 who come here,'' said Raul Rodriguez, a chef at La Cuija, a posh restaurant,
 which offers dishes such as cow's tongue and, occasionally, rabbit. ``I'm sure a
 lot of the local people eat it at home, but they might not admit it because of the
 stigma.''

 Even so, demand for the rodents at times is so great, that vendors who come in
 from the farms to sell their animals at the local market on weekend mornings
 usually run out of their supplies within an hour.

 Unlike the scavenging city rats better known for scurrying through garbage
 dumpsters and sewers, field rats eat mostly grains and seeds planted on farms,
 experts and rat-eaters say, giving them a higher nutritional value and a better
 taste.

 ``They're rich in iron and protein, and more affordable for a poor family than buying
 meats, vegetables and fruits,'' said Teresa Ochoa Rivera, a health professor at the
 Iberoamerican University in Mexico City. ``But as with other meats, it depends on
 careful handling and preparation.''

 Does it taste like chicken?

 ``Actually, it tastes better,'' said Manuel Samaniego, 34, who manages a crafts
 shop in the city's historic center. ``It has a sweeter taste, more like rabbit.''

 RAT-CATCHER

 To catch his rats, El Yuri wakes up at 3 a.m. to check the wooden traps set out
 in the field the night before. The animals are then killed and skinned before he
 drives to the city market, where he arrives by 8 a.m.

 In the past, vendors used to spread their offerings on a sidewalk -- rabbits on one
 side and skinned rats stretched on a skewer on the other. Each rat sells for about
 $2.

 But now, El Yuri has to crouch carefully behind a market wall and keep his
 animals tucked secretly in bags because local health officials have clamped down
 on rat sales after one vendor was reportedly caught selling city rats instead of the
 field kind. Two people reportedly died from mistakenly eating city rodents.

 ``It's not that this is embarrassing so much as it is a health issue,'' said an official
 who requested anonymity. ``Selling and eating rats is not a formal part of the food
 sector so there are no regulations to monitor it. We don't want more cases of bad
 rats.''

 But in a place where Big Macs and Whoppers are quickly becoming the new
 culinary standard -- Zacatecas recently got its first Burger King -- rats, like
 worms, fried crickets and grilled snake, will probably fizzle out on their own,
 without government help.

 Nevertheless, the tradition for the Herrera sisters will remain alive so long as there
 are colds, flus and fevers to cure.

 ``It works in minutes,'' said Catalina, 24, as she stood in the kitchen of the
 family's Rancho Grande restaurant. ``You can't eat it all the time because it's so
 powerful. Once you get past the thought of eating a rat, you'll see that it's not
 what you think.''