Esposto's can make 10,000 bag lunches a day for hungry firefighters on the lines.
Last year, they delivered tens of thousands of the meals for firefighters working 12 to 24 hour shifts exhausted by the heat, intense winds and physical challenges.
VIDEO: Here is what tired, hungry firefighters are eating on the front lines
Patriarch Bill Esposto runs the business with his sons Garbriel and Victor. He says Cal Fire has strict specifications for the meals.
The meals must contain between 4,000 and 6,000 calories in a bag lunch says Esposto.
"A certain amount of protein. A certain amount of carbs. Dried meat. Fruits and vegetables," he said.
Along with the veggies and fruit, a typical meal would also have electrolyte drink mixes, beef jerky, protein bars, trail mix even olives from Italy.
There's no pressed meat in the sandwiches.
They carve and slice their own says Gabriel Esposto. "Since we own delis, we try to do different sandwiches and not just turkey sandwiches."
RELATED: Guy Fieri feeds hundreds of Carr Fire evacuees
They also have vegetarian burritos, which firefighters don't need to microwave.
"We can wrap it in foil and you put it on your engine block and that's how you heat it up," says South San Francisco Fire Battalion Chief Chris Campagna.
All their bread and cookies are made in Esposto's own bakery. And they have to do all this quickly.
Victor Esposto says the calls from Cal Fire come without warning.
"It could be two in the morning when we get a phone call. They say they need lunches delivered four hours away within ten to twelve hours," he said.
"Good quality food on a short notice is really something we appreciate," says South San Francisco Batt. Fire Chief Matthew Samson.
For more stories, photos, and video on recent fires burning in California and across the country, visit this page.
Ever wonder what tired firefighters eat when they’re battling never ending wildfires? Watch ABC7news tonight pic.twitter.com/dAboTLnGXp— Vic Lee (@vicleeabc7) August 21, 2018
Caterer to Calfire made 80,000 meals for firefighters battling wildfires last year...just made 3,000 meals on Sunday. pic.twitter.com/aWL9wsombj— Vic Lee (@vicleeabc7) August 21, 2018