The beer is cold and so is the guacamole when the snapper hits the grill.

For hours, several whole fish have marinated in a chile-and-garlic seasoning, a specialty of Mexico's Yucatan Peninsula.

Now, they will be briefly charred and then wrapped in banana leaves so they may finish in a kind of tropical steam bath, staying succulent and moist.

No longer is this a back yard in Catonsville. It is a beach on the Gulf of Mexico. Fresh fish roasting over hot coals, a primordial mix since men first started casting nets into the sea. The smells are sensuous and exotic.

Chef Michael Marx, owner of Baltimore's Blue Agave, is demonstrating that the marriage of backyard grilling and Mexican regional cuisine is a natural fit. Robust flavors. Simple technique. Hot chiles over hot coals.

The results are spectacular. If this weren't a Tuesday afternoon - and the tree-lined neighborhood practically evacuated at midday on a workday - the neighbors would no doubt be storming the back yard for a sample of the smoky, spicy seafood served with grilled corn on the cob, chips and salsa.

"Ultimately, it's about simplicity," says Marx, a San Diego native who opened his critically acclaimed Mexican restaurant one year ago. "That's the beauty of this kind of cooking."

Marx should know. He grew up with it. His family often did its grocery shopping south of the border. He made forays into South and Central Mexico long before he contemplated a life in restaurants.

Mexican cooking has never been a one-note cuisine, but a broad palette with distinct and subtle flavors from its varied regions. It is like the difference between New England clam chowder and a Southern hush puppy.

But outdoor cooking is almost universally loved throughout Mexico. From street vendors in Mexico City to open-pit cooking on a Baja sand dune, the idea of roasting meat or seafood over charcoal or wood has been at the heart of Mexican cuisine for centuries.

That tradition has finally taken hold in the United States, and a host of products, chiefly seasoning rubs and marinades, has hit supermarkets from coast to coast to spice up the humdrum backyard menus of burgers, steaks and chicken breasts. But none of these packaged seasonings is truly necessary for authentic Mexican grilling; usually just a backyard grill and a few basics such as garlic, lime juice, cilantro and chiles can suffice. (Don't be confused if your market calls them "chilies." That's the Anglo-American spelling.)

Rick Bayless, a Chicago chef and host of the Public Broadcasting Service cooking series "Mexico One Plate at a Time," believes the novice can start with good-quality ingredients and let the most important source of flavoring - the fire - do most of the work.

"Everybody goes for the simple meat tacos cooked over a simple charcoal or wood fire," says Bayless, who is currently shooting video for a new PBS Mexican cooking series this fall. "It's a regional specialty of northern Mexico. The pieces are sliced thin, salted and chopped small because it's usually not high-quality meat. But it's probably the best thing you can ever eat."

He also believes that good-quality Mexican food need not be difficult to cook.

The techniques are much the same as any backyard chef uses to grill steaks, chicken, fish or vegetables - direct or high-heat cooking to sear and medium-heat, indirect cooking to finish.

One of the simplest dishes he recommends is a Mexican version of grilled steak or carne asada. Just marinate the steak in lime juice, garlic and salt for an hour or two, spray with oil and grill. Serve with guacamole, salsa, cooked beans and a salad made with grilled cactus paddles.

In his own back yard, Bayless generally cooks over charcoal, throwing in a few wood chunks that have been soaked in water. Recently, he acquired a gas grill and appreciates its convenience.

"I'm one of those lovers of charcoal fire. It's not that much effort to build a fire, but I know most people find a gas grill easier," he says. "There are times when I choose it, too. Like in the middle of winter when you don't want to be outside for very long."

When Patricia Quintana talks about Mexican grilling, she makes it sound even simpler. The owner of a noted Mexico City cooking school, Quintana is often cited as a major influence in the growing interest in regional Mexican cooking in the United States.