The Cast Iron or Tubular Range
Heat oil in a large skillet over medium heat.
Add onions; cook, stirring occasionally, until the onions are slightly browned and somewhat soft, about 10 minutes.
Stir in the ketchup, brown sugar, chili powder, hot sauce and cinnamon; mix well.
Add the water and bring mixture to a boil; simmer, uncovered, until onions are completely tender and the liquid is mostly evaporated, an additional 10 minutes.
Turn off the heat, remove the lid from the pan, and let the onions cool for a few minutes. Give them a taste, then add salt and pepper as desired.