Homemade Ketchup Recipe

1 Heat the oil in a medium saucepan over medium-high heat. Add the onion and cook, stirring occasionally, until the onion is tender, about 8 minutes.
2 Add the remaining ingredients; bring to a boil.
3 Reduce the heat and simmer, uncovered, stirring often to prevent scorching, until the ketchup is thickened and the flavors are blended, about 1 hour.