Steam is hot.

So hot, it's lifting the $28 billion frozen-foods industry out of the deep freeze. ConAgra Foods last week announced plans to roll out this summer Cafe Steamers — a line of 12 Healthy Choice meals — that can be steamed in the microwave in special containers.

ConAgra is one of several food giants that that have been introducing the United States to steaming technology — already used in Europe and Japan. It is now using it for entire meals.

Consumers seem gaga for microwave steaming. After suffering through five flat years, frozen-veggie sales closed 2006 up more than 6 percent, led by Birds Eye's rollout last year of Steamfresh vegetables. Green Giant followed with veggies, and now comes Con Agra with meals.

"Steaming will do for frozen vegetables what the iPod did for music," says Bill Partyka, a vice president at Healthy Choice.

Information Resources, a product research specialist, says Birds Eye Steamfresh will be one of 2007's fastest-growing foods.

Nutritionists say that microwave "steamed" food may look or taste better, but it's not healthier. "If the novelty makes people eat more vegetables, that's good — but the rest is hype," says Neal Barnard, nutritional researcher and author of "Breaking the Food Seduction."

Says Chris Rosenbloom, nutrition professor at Georgia State University: "It sounds like a marketing ploy. It certainly doesn't make me want to stock my freezer with them."

The new technology also does not come cheap. Cafe Steamers are up to 30 cents more than similar meals. And Birds Eye veggies in the Steamfresh pack are up to 25 percent more expensive.

Here's what's cookin':