You can’t go wrong with a good old fashioned classic patty melt, and Sonic did this one right.

Toasted Texas toast, grilled onions, mayo, cheese, and beef patty. The non-traditional add in is they also have mustard, so you can ask them to leave that out if you want.

$3.99 is the special price, I can’t tell if a double is available for cheap too, but it would likely be about $1 upgrade to make it a double.