Thank you, Linda. I would like to thank you for joining us on the call today as well as for your continued interest in The ONE Group.
I'm pleased to report that 2018 is off to a strong start, as we built upon our fourth quarter 2017 momentum in comparable sales, restaurant-level margins and adjusted EBITDA. Comparable sales grew 6.6%, including a 7.2% increase in the comparable sales from our domestic owned and managed STK units. While internationally, we saw an increase of 4.5% in comparable sales from our managed venues.
We believe that the latter was impacted by unsellable weather in the U.K. during the quarter. Restaurant-level profitability increased over 400 points, despite rising beef costs and an increase in minimum wage across most jurisdictions where we operate.
And adjusted EBITDA grew 11.6% to $1.8 million despite a 2017 nonrecurring Super Bowl party hosted in Houston, Texas, which impacted year-over-year growth at $700,000 or approximately 45%. Throughout this year, we plan to execute against our long-term 4-point strategy implemented in 2017 to drive sales, profitability and ultimately, shareholder value.
As a reminder, these include: one, improving operational efficiencies in our restaurants; two, driving comparable sales; three, reducing G&A at corporate level; and four, focusing on growth through license and management deals only. At the restaurant level, we are identifying operational opportunities that we believe can help improve performance, enhance margins and increase profitability.
Some examples include reducing waste by streamlining so many options or effectively managing labor scheduling and reevaluating service contracts at the restaurant level. The results of these efforts are ongoing. They have already resulted in reduction of cost of sales, and restaurant operation expenses as a percentage of owned restaurant revenues that we experienced in the first quarter.
Next, we continue to implement many sales driving initiatives that we believe that we can build upon throughout the year. We are fully focused on improving our restaurant sales and guest counts by delivering an exceptional dining experience for each guest, at each meal, each and every day.
Similar to last year, we are promoting STK gift cards and we're working on building relationships with the concierge desks at high-profile hotels near our restaurants. We recently reintroduced brunch at select restaurants, providing an energetic [vibrunch] experience.
And finally, subsequent to the quarter-end, we launched Social Hour by STK the in all our restaurants to promote the Happy Hour daypart, offering limited time drinks and small plate promotions.
As a reminder, we are also testing delivery at select restaurants, with several different delivery partners and are encouraged by what delivery could potentially mean long term for our company. While it's still early, we are pleased with the results we are seeing thus far through these efforts.
Turning to development. We are focusing our growth on asset-light management and license deals. And believe over the long term, we can efficiently manage 3 to 5 license deals and one to 2 food and beverage hospitality projects per year. Looking at 2018, specifically, we plan to open 4 international licensed STKs, while our company-owned STK in San Diego, California is nearing completion.
We're continuing to see strong interest for the STK brand and in our hospitality program globally, and I'm excited by our 5 points of asset-light license and management opportunities. Our guests certainly appreciate our unique, highly-differentiated dining and hospitality experiences, because it provides best-in-class dining, combining superior quality steak house, with an innovative menu and a vibrant launch.
As a result, our guests, they stay to enjoy additional drinks once the meals are complete, listen to our DJs, and extend their evening. I expect these experiences will continue to drive opportunities for the ONE Group and our licensing partners globally.
Following the opening of STK Dubai at the end of last year, we plan to open 2 licensed STKs in the Middle East during the second half of this year. These include an STK in downtown Dubai, and an STK in Doha, in the city's newly-renovated Ritz-Carlton Hotel.
Additionally, during 2018, we plan to expand our footprint into Mexico. First, a full licensed STK is planned for the region, is planned to open in Mexico City during the second half of the year. The remaining 2 locations are slated for 2019 and 2020, Guadalajara, Monterrey and Cabo.
Our license partner in Puerto Rico continues to work hard, recovering from the 2 major hurricanes that occurred in 2017. With the information we have at this time, we believe that at least one of the 2 planned San Juan restaurants should open by the end of 2018. We will provide further updates once we know more.
Finally, after much anticipation, in early June, we plan to open our only company-owned unit in development, STK San Diego. This location is located in the historical Gaslamp quarter at the Andaz Hotel. This restaurant will be in addition to the already existing licensed and operating STK hotel rooftop.
Lastly, as you may have read last month, STK was named to OpenTable's 100 Best Restaurants in America for a big night out. This accolade is a testament to the high energy and great atmosphere our restaurants offer, and a great honor for our brand. I would like to thank the entire ONE Group team, whose hard work made this achievement and all our recent successes, possible.
With that, now I'd like to turn the call back to Linda, who will provide more detail on our financial performance for the first quarter, as well as discuss guidance for 2018. Linda?