Since opening its first store in 1971, Starbucks has come a long way from being known as "just a coffee shop." As the company has grown at a monumental pace, it has moved beyond the traditional coffee- and tea-based menu offerings in an attempt to stay competitive with other fast food restaurants.

Identifying a niche market of health-conscious millennials, Starbucks is aiming to expand its lunch menu to include sandwiches and salads, competing with other fast-casual food vendors like Panera and Chipotle. And they aren't the only ones — fast food restaurants across America are looking to take their menus to the next level, as well.

The summer of 2015 first marked Starbucks' declarations of further breaking into the fast-casual food industry. At the time, Business Insider reported that several limited-time offers would be tested out at Starbucks stores across the country, including "superfoods bistro boxes" and prosciutto and mozzarella pinwheels, to name a few.

A report by Goldman Sachs noted that with more than 20,000 locations worldwide, Starbucks could bring some serious competition to McDonald's. And sure enough, Starbucks began to offer child-friendly items to compete with the Happy Meal, including healthier options such as string cheese, fruit squeezes and Greek yogurt.

Two summers later, how has Starbucks fared? A recent article from Progressive Grocer notes that Starbucks is "redoubling" on its lunch efforts, as over 50 percent of Starbucks customers come in after 11 a.m.

The company has grown its food options 1.5 times since 2013, and is aiming to double this by 2021. Still going strong on its target of catering to the tastes of health-conscious millennials, Starbucks' new lunch menu, titled Mercato, is looking to increase vegetarian-friendly and protein-filled options.

The Starbucks of the future could very well be selling seared steak and mango salads, one of the items currently being tested at 100 locations in Chicago. However, they don't plan to completely abandon coffee, or treats deemed as less healthy.

Earlier this year, Starbucks announced that it was debuting ice cream at more than 100 stores across the United States with a twist. The chains added affogatos to their menu, an Italian treat that sees a scoop of ice cream topped with a shot of espresso. In Seattle, this became a top-five selling item.

Starbucks isn't the only chain to diversify their product line. Fast food chains have discovered that adding alcohol to their menus has attracted customers and allowed for reinvention.

While Chipotle has long been selling margaritas, Burger King recently started selling alcohol in New York City, and Taco Bell is aiming to roll out a "cantina-style" prototype of their restaurants. In offering alcoholic beverages, they are looking to keep customers in the restaurant longer, thus having them spend more money, thus bolstering profits.

In 2006, the founder of Shake Shack backed a salad chain called Tender Greens, which has 25 locations in California. In 2016 alone, the company made over $80 million in sales, with annual revenue growing 20 percent year-over-year.

Their menu goes beyond the traditional salad, and offers dishes such as flank steak and fried chicken with a rotating menu of seasonal sides. Ingredients are sourced from local farms, ranches, wineries and breweries, giving each location a unique variety of items to sell. With each dish priced around $12, Tender Greens offers patrons an affordable yet elevated dining experience.

Beyond the in-store experience, restaurants have been using mobile apps and digital ordering systems to appeal to customers looking to skip the line. Starbucks' Mobile Order & Pay platform rolled out last year, and now Denny's is looking to get into the same digital market. Fortune reports that "Denny's on Demand" will offer digital ordering for mobile and online users, allowing them to place an order for takeout or delivery.

Another fast food chain to (finally) start offering delivery is McDonald's. Through the UberEATS mobile app, McDelivery is being offered at more than 1,000 restaurants across the country. McDonald's launched a delivery platform in Asia and the Middle East last year, and made $1 billion in sales. With an American expansion on the horizon, the definition of fast food as we know it will continue to evolve.

While Starbucks does not have any plans for a delivery platform, they very well could offer it in the future. Given the popularity of their revamped lunch menu, their current ambitions seek to gain further ground in the market to become a major player among the competition.

With digital programs and mobile apps constantly expanding, customers are looking for the added convenience of skipping the line, and Starbucks is hoping their gourmet-yet-health-conscious offerings will help. A seared steak and mango salad? Dishes like this may even start to cut into higher-end restaurants' profits.