- set the veggies aside
- put the whole burger in the microwave upside-down on a plate for half the time it takes to reheat (usually 30 seconds for this step if cold from the fridge)
- flip it and nuke it for the rest of the time
- restore veggies to rightful place
I was amazed the first time I did this and had a 100% sog-free bun. The burger was indistinguishable from fresh. I don't know exactly what's going on, or what's different from just nuking it all the way on one side, but it works. I've tested this on burgers from Wendy's and Hardees (aka Carl's Jr.). You might need to adjust depending on how formidable the burger is and your microwave's wattage.