The croque madame, a French favorite, is gaining popularity on menus.

Sandwiches are featured more prominently on food service menus than similar handheld fare, such as burgers, hot dogs and pizza, said Packaged Facts, a Rockville-based research firm. Nearly three-fourths of quick-service restaurants and 62% of fine-dining restaurants serve sandwiches.

Many operators are reinventing the lunchtime staple with gourmet twists and global flavors.

“Leveraging progressive food sourcing and food preparation practices, restaurants and food manufacturers are increasingly focused on providing sandwiches that are fresh, naturally produced, locally sourced, and either culturally authentic or genuinely creative in culinary concept,” said David Sprinkle, research director of Packaged Facts. “This focus dovetails with two of the most important consumer drivers in the sandwich market, the demand for flavor adventure and authenticity.”

Packaged Facts identified eight sandwich types trending on restaurant menus and in retail outlets, driven by international or regional influences and demand for bold flavors and healthy options.

1. Garden tartines

Fresh produce piles high on a single slice of bread to create an enticing and vegetarian-friendly “still life of a sandwich,” Packaged Facts said.

2. Tortas and cemitas

A growing interest in international sandwiches and street foods has given rise to two Mexican mainstays. Typically served on a long crusty roll, tortas may be eaten cold, hot, grilled or toasted with such fillings as avocado, poblano, jalapeño, ham or adobo meat. Cemitas commonly are served on an egg roll topped with sesame seeds and may include carnitas or beef milanesa, which is a thin, fried piece of beef, topped with shredded or hand-pulled Mexican string cheese.

3. Croque monsieur and madame

The rise of global cuisine gives way to the resurgence of two familiar French favorites with modern-day tweaks. Conventional croque monsieurs are grilled ham and cheese sandwiches with béchamel sauce. The croque madame comes topped with a poached or fried egg.

4. Brisket sandwich

Rooted in the comfort food trend, brisket is hot even on non-barbecue menus, Packaged Facts said. This versatile meat may be served in a number of ways, from classic to distinctly contemporary, Packaged Facts said.

5. Cuban sandwich

Featuring layers of ham, roast pork, Swiss cheese and pickles, the panini-style Cuban sandwich is in the midst of a revival, as chefs experiment with new ingredients and upgrades.

6. Sweet and savory sandwiches

Sweet and savory combine to create a sophisticated twist on traditional sandwiches. Usage of jam in sandwiches served in restaurants rose to 11% in 2014, with use in hot sandwiches nearly doubling during that time, Packaged Facts said.

7. Protein-based salad sandwiches

Classic tuna, chicken and salad sandwiches have gone gourmet in recent years with fancier fillings, condiments, breads and sides, Packaged Facts said.

8. Breakfast sandwiches

Handhelds are a hit in the morning, when many consumers are grabbing breakfast on the go. Operators may appeal to more consumers by leveraging such descriptors as “natural,” “local,” “seasonal” or “sustainable,” which are four times more likely to appear on non-breakfast items, said Packaged Facts.