Eat24 is a Web and mobile food ordering service that's grown like crazy in the last few years. What started as two guys in a San Francisco apartment in 2008 has grown to 150 employees, 20,000 restaurants available in 850 cities, more than 1 million visits to its website a month, and a projected $150 million in sales this year.

A good part of Eat24's success stems from the way the bootstrapped company uses social media. Here's their recipe for success.

Step 1. Answer everyone.

Admittedly, this strategy isn't going to work for every start-up. Eat24 is never closed, so there's always someone who has a window into what's going on online. "We have 24-hour customer service, so say a tweet comes in at four o'clock in the morning and it's something above the level of customer service. They will call and wake up someone on the marketing team who help on the response," says Eat24 co-founder and CEO Nadav Sharon.

So whether it's interacting with customers on Facebook, Twitter, Yelp, YouTube, Pinterest, Tumblr, LinkedIn, Google+, or its own blog, across all these touch points the company says it tries to answer every comment posted by customers and fans--whether it's retweeting customer tweets, replying to mentions, or following people. It's no small feat--in a given weekend Eat24 could get hundreds of mentions on Twitter alone.

Step 2. Develop a strong voice.

But what really makes the brand strong, says Eat24 social media manager Patty Jordan is its consistent and authentic voice. She's not kidding; the company blog, for example, is actually something you'd want to read. Not only is it witty, it offers people coupons to get them coming back, then says things like, "Want another coupon? No problem. Ask us nicely on Facebook or Twitter," which just keeps the engagement ball rolling.

One Eat24 tweet reads, "Need to break the awkward silence between you and your cat? Visit the Eat24 YouTube page. If you follow the link, you'll land on clever videos with titles like "Embrace your inner sloth," which has garnered nearly a half million views--not bad, considering it's an ad.

Not only do all these channels constantly point to each other and give customers reason to engage with the company, Eat24 social media manager Patty Jordan says they make customers feel like they're talking with people, not a robot or business. "That's sort of our brand voice," she says. "We can be pretty sassy and that does sometimes rub people the wrong way, but I kind of also feel like that's what makes the brand strong... when you just go for it 100%," she says.

Step 3. Automate smartly.

The Eat24 voice does sound like a person, but that's not to say bots of a sort aren't involved. After customers place an order they land on a "Thank You" page that gives them the option to tweet their meal. Eat24 used the Twitter API to make this work, and lets customers pick from funny phrases such as, "Yes, I just ordered @eat24. No, you can't come over," or "I'm doing my part for the economy and ordering out with @eat24. I'm not even #hungry. I just love America."

"The brand voice isn't written in a manual. It's a mentality that runs through the entire company, so whether you talk to someone from sales, support, social media, you'll get the same voice. It's truly who we are. We do work 24 hours a day. It's not just a clever name," Jordan says.

Like the idea of a brand that tries to be "real?" Check out my recent post On Social Media, Authenticity Always Wins.