Hot water constitutes a significant amount of my "cooking".
Coffee, instant stuff (ramen, etc), dehydrated stuff.
For making hot water Jetboil is king of the mountain 16oz boiling water in about 2 1/2 minutes (dependent on temperature of water and altitude) an $8 adaptor will let you run it off of propane if you don't want to carry two kinds of fuel.
I reserve the more elaborate 2 burner and proper meal preparation for when I am stationary for the remainder of the day generally.
I also have gear for open fire (campfire) cooking.