There was a time when I made frequent car trips back and forth between the Bay Area and Southern California. The Route 5 interstate was fast but boring, and I always took a break at an Arco gas and snack station that served cheap steam table burgers.
The burgers were absolutely nothing to write home about—tasteless and textureless, made more so by extended storage at a food-safe temperature in a foil-coated paper wrapper. But what saved them was the unusual onions—dehydrated and reconstituted—that were available in a stainless steel tub. A few scoops of these onions combined with mustard, pickles and maybe some jalapeños and I was good to go.
The dehydrating process made the onions sweeter while concentrating the onion flavor. One of these days I’m going to try making my own dried onions at home. (Directions like on this site suggests you should par-roast the onions before dehydrating, which accounts for the sweetness.) For now, you can get something pretty close in Toné’s Minced Onions, available next to Toné’s Chili Powder at Sam’s Club.
To prepare, just mixed the dried onions with an equal amount of water and microwave 30 seconds or so while you’re cooking your burger. My only complaint is that the diced onions, unlike sliced, tend to fall off the bun. You can correct this, if you’re an onion lover, by putting the Toné’s INSIDE the burger and putting still more more (raw) onion on top.