Shares of Portillo's (PTLO 0.42%) took flight Tuesday morning, jumping as much as 18.9%. As of 1:18 p.m. ET, the stock was still up 13.3%.

The catalyst that sent the fast-casual restaurant stock higher was the company's preliminary financial results, which were surprisingly robust.

Tasty results

Portillo's made a presentation at the ICR Conference this week, and the company provided preliminary results for the fourth quarter, which were much better than investors had feared. The biggest surprise was same-store sales, which increased 0.3% year over year, well ahead of analysts' consensus estimates of a 1.1% drop, and management's guidance, which implied a 0.8% decline.

At the same time, preliminary revenue of $184.6 million was ahead of the $184.4 million expected by analysts. Full-year preliminary revenue of $710.6 million increased 4.5% year over year, just below the $710.9 million expected by analysts.

Management also provided its internal forecast for 2025, guiding for same-store sales to increase roughly 1% year over year at the midpoint of its guidance, while forecasting revenue growth of approximately 11% and adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) to increase by about 7%.

It's the economy

The past couple of years have been difficult for restaurant stocks. Historically high inflation has jacked up food prices and labor costs, even as many consumers made tough choices to make ends meet.

As a result, restaurant traffic in the third quarter was down 3% year over year and 17% below Q3 2019, according to CREST Research. The combination of less foot traffic and higher input costs has weighed on restaurant results.

The fact that Portillo's was able to increase same-store sales -- even by a little -- gave investors cause to celebrate -- especially as there were much greater declines suffered by the rest of the industry.

Despite the difficult economy, Portillo's offers a compelling opportunity, selling for 24 times earnings, an intriguing multiple for a company that's outperforming its peers.