If there's a good deal on the table, don't hesitate to jump on it. That's the takeaway from the latest episode of Shark Tank, where Mark Cuban offered an entrepreneur a six-figure investment as long as she didn't negotiate or take too long to decide. 

Jenny Goldfarb was pitching Mrs. Goldfarb's Unreal Deli, her line of plant-based corned beef that's sold online and in delis and restaurants, on Sunday's episode of the ABC reality show. She was seeking $100,000 for 10 percent equity in the L.A.-based business, which makes the vegan deli meat from beets, chickpeas, and tomatoes. 

Goldfarb created the product after she became vegan five years ago--she made the decision as a result of watching videos on animal cruelty, she told the sharks--but missed the deli meats that had played a role in her family's history. Her great-grandfather immigrated to the U.S. from Romania as a teenager, she said, without his parents or English-language skills. He started working in a New York City deli as a dishwasher, then made his way up to owning several delis and cafeterias in the city. Turns out, one of Cuban's relatives also came to the U.S. from Romania, he told the entrepreneur. 

"For us to be sitting here on this stage today, it's what our parents and grandparents did for us to get here," Goldfarb said. 

Her company, which was only a few months old when she filmed her Shark Tank appearance, has sold about $10,000 worth of products through delis. Additionally, the startup's recently launched online store sold $2,000 worth of vegan corned beef (at $26 a pound) in the first 24 hours, she told the sharks. Mrs. Goldfarb's Unreal Deli expects to expand into 53 Whole Foods stores this year and two large restaurant chains in January, and projects $3 million in sales next year. 

A few sharks expressed concerns about how Goldfarb will compete with Silicon Valley heavyweights that have raised more funding and are likely to expand into plant-based deli meats. Among them was guest shark Anne Wojcicki, co-founder of at-home ancestry and health test 23andMe, who said she has invested in similar companies. 

Goldfarb noted that investors have already shown interest in her product, but that she wanted to work with a shark who could help her scale the company. "One shark dollar is worth five regular dollars," she said. 

Kevin O'Leary made an offer, but Cuban undercut him with a better one--$250,000 for 20 percent equity, which increased the company valuation by $250,000 to $1.25 million--and told her she needed to decide immediately. Cuban often proposes deals that are "take it or leave it," meaning entrepreneurs can't haggle or hear other offers before deciding. 

"This business is a cash cow," Goldfarb said after accepting Cuban's offer and leaving the Tank. "We're making cash and we're saving the cows."