The caterers make thousands of meals for businesses and private events. One of their clients is Cal Fire, and it's been a busy year serving them.
Esposto's can make 10,000 bag lunches a day for hungry firefighters on the lines.
In 2017, 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 Gabriel and Victor. He said Cal Fire has strict specifications for the meals.
The meals must contain between 4,000 and 6,000 calories in a bag lunch Esposto said.
"A certain amount of protein. A certain amount of carbs. Dried meat. Fruits and vegetables."
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.
"Since we own delis, we try to do different sandwiches and not just turkey sandwiches," Gabriel said.
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 said the calls from Cal Fire come without warning.
"It could be two in the morning when we get a phone call," he said. "They say they need lunches delivered four hours away within 10 to 12 hours."
"Good quality food on a short notice is really something we appreciate," said South San Francisco Batt Fire Chief Matthew Samson.