"Did you guys change the chile con queso recipe?" I ask the waitress as I slip a chip into the bowl of average-tasting cheese dip. She can't say exactly, but she sends the manager on duty to my table. I ask him the same question.

"Is something wrong with the queso?" he wants to know.

"It tastes fine to me," I say. But people are talking.

"Yes," the manager says, the recipe changed about a year ago.

"What's different?" I want to know. He hems and haws.

"Are you using powdered cheese?" I ask.

"No," he laughs. In fact, he says, there was powdered cheese in the old queso recipe. The big switch is that Los Tios is now using real cheese.

"Is the new cheese Land O' Lakes Extra Melt?" I guess. (Extra Melt is the cheese of choice for many Tex-Mex restaurants.) The manager suggests I call the head chef.

The new head chef of the four-restaurant chain, Roberto Ozeata, is a Guatemalan-American who used to work at Carrabba's Italian Grill. He's trying to keep the old Los Tios menu intact while adding a few modern chef's specials. When the subject turns to Los Tios's chile con queso recipe, he covers the phone with his hand. In a muffled conversation, I hear him asking someone for advice. When he puts the phone back to his mouth, he can't talk about queso anymore.

"Call Gary Adair," he says, directing me to the owner of the Local Concepts restaurant group, which owns Skeeter's, Los Tios and several other Houston restaurants.

"But I'm interviewing you," I object. "You can't talk about this?"

"No, sir," Ozeata says.

The cheesy hot potato has now been handed from the waitress to the manager, to the head chef, to the owner of the chain. By the time Adair calls me back, my question has become: "What's the big deal?"

"The original Los Tios was blocks from my house when I grew up. I ate there since I was 16," Adair begins. "People are so loyal and so finicky about their Tex-Mex -- you have to respect it." When he first bought the chain, he says, "My mother grabbed me by the throat and said I couldn't change anything."

Adair figured that remodeling the restrooms, which needed to be brought up to code anyway, would be an innocuous improvement. But even that was met with dissent. "A woman I've known for a long time told me, 'I am so sorry you changed the restrooms.'" It turned out that many years ago, her husband had dropped to his knees in the Beechnut Los Tios and asked her to marry him. She ran with her girlfriends to the restroom, and that's where she asked them to be her bridesmaids.

If updating the bathrooms creates controversy, imagine what happens when you change the queso. When Adair bought Los Tios in 2001, he agreed to buy the queso and some other preparations from the previous owners' Tex-Mex manufacturing company, he explains. But when the contract was completed about a year ago, the restaurant began to make their own. He never got the original recipe for Los Tios's chile con queso. And he will not confirm or deny that it was being made with powdered cheese.

"When we first started making our own recipes, the first couple of weeks we had some glitches," he admits. "But we are real proud of the queso now."

"It's Land O' Lakes Extra Melt, right?" I ask.

"Yes, that's right," he confirms. And that's the top-quality cheese for chile con queso, he reminds me.

"We use Velveeta and Rotel tomatoes in the queso at Skeeter's," he says. "The Skeeter's queso is simpler, and we serve a lot more of it -- it's a kids' place. The Los Tios queso recipe is more complicated." He says the queso at Los Tios today tastes fresher than ever.

"There was a storm when we first started making it ourselves," he says. "It took us a while to get it right. And now the storm is over and the skies are bright."