But it's this on-site assembly that could be problematic. Alicia Syrett, a board member of New York Angels, said she's worried about Bento's ability to comply with food-safety and sanitation standards.
Demant stressed that once food leaves the kitchen the driver doesn't open the containers. He added: "That's how our whole system is built and modeled. We've gone through all the necessary regulations with the San Francisco Health Department and any cities we expand to in the future, we'll do the same."
Nikhil Kalghatgi, a partner at Vast Ventures, questioned how Bento expects to compete with other on-demand food players.
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Demant said that unlike its competitors, Bento let's people customize every part of their meal. "You're really getting the exact meal that you want," he said.
For now, Bento only delivers in San Francisco, but the CEO told CNBC the start-up has plans to expand to Oakland and Palo Alto by the end of this year.
The company launched in March 2015 and has raised $325,000. Bento is seeking $1 million in its seed round and currently has seven employees.