Combine all ingredients in a small saucepan, stirring with a whisk until smooth. Bring to a boil; reduce heat, and simmer 25 minutes, stirring occasionally. Cool completely. Cover and store in refrigerator up to 2 weeks.
Tip: I have gone a bit crazy trying to get high-fructose corn syrup out of my kids' diet, so I've started buying organic ketchup, which doesn't have any. It's delicious.