Duke's Old Fashioned Onion Burgers brings Oklahoma-style smash burgers to La Mesa's Fletcher Hills corridor from a converted storefront at the corner of Baltimore Drive and El Cajon Boulevard. The onion burger method presses a ball of ground beef into a bed of paper-thin onions on a hot griddle, caramelizing the onions directly into the patty to create crispy laced edges — a Depression-era technique that pairs with the pour-over and single-origin coffee culture at Brew Coffee Spot in La Mesa's artisan food scene. Founded by Frank Schultz, who spent 34 years in Tulsa before returning to his native San Diego, the restaurant opened in 2022 with a ribbon cutting hosted by the La Mesa Chamber of Commerce and attended by La Mesa's mayor. All condiments — ketchup, pickles, and dressings — are made from scratch on-site, and every burger ships on a toasted brioche bun with fresh-cut fries and hand-dipped milkshakes. The counter-service format and Health Department score of 96 out of 100 position the kitchen alongside the Southeast Asian noodle preparations at Pho Superbowl as a from-scratch alternative on the Baltimore Drive corridor. The double onion burger stacks two smashed patties with a double layer of griddle-caramelized onions, American cheese, and Duke's house-made sauce on a single brioche bun.