“It is one of the four great cuisines in the world,” he says, citing French, Chinese and Italian as the other three.

In the storeroom of his downtown restaurant, he opens the fridge and shows off all its contents.

He brings forth Arrezio mozzarella (“I tried 100 different kinds before I knew that this was the best!”), maíz flown in from Texas, 12 different varieties of chili peppers (kept in black bags to maintain their spiciness) and chicken, beef and pork still fresh and refrigerated (never frozen, as he claims other restaurants do).

Espinoza says he can’t bear to think any aspect of his restaurant is less than perfect.

“Whatever I do, I want to be number one at it,” he says.

In fact, his next ambition is to take a bite out of Taco Bell.

“Right now, they have no competition,” he says. “I know it’s crazy, but that’s what I want to do.”

But even that ambition pales in comparison to his true life’s passion: He wants to “change Mexico from the roots.”

“It is not too much to say that I want to revolutionize the government,” he said.

Espinoza left Mexico City in 1994 after the assassination of reformist presidential candidate Luis D. Colosio, under whom Espinoza was director of private affairs.

“I was faced with a choice,” he says. “I could either continue to work in Mexico for a government that is corrupt and that I don’t support, or I could make a break in my life.”

He acquired a 27-year resident alien permit and came to Cambridge to continue his education at the Extension School.

“I want to have enough resources to finish my doctorate and get involved in politics again in Mexico,” he says. “But I don’t want to have to take dirty money for my campaign.”

He plans to write his Ph.D. about poverty in Mexico, where today about 27 percent of the population lives under the poverty line, according to CIA statistics.

Espinoza says his family back in the Mexican state of Sinaloa are upset with him for having put his most important goals on hold for tacos.