How do you improve upon a classic? By making the beef taste beefier. We found that treating the ground beef with baking soda (so that it retained more moisture when cooked) and then breaking it down to a fine, uniform texture in the skillet delivered a tender, flavorful, and cohesive mixture that stayed put when placed on a bun. Limiting the aromatics to just onion (also treated with baking soda to soften it) made for a beefier-tasting mixture with a rich, luxurious texture. We made ketchup's sweet-tangy flavor more complex by adding vinegar, red pepper flakes, and sugar and balanced it out with generous amounts of tomato paste, paprika, and Worcestershire sauce. Finally, we served it all up on soft hamburger buns.